y g o l o iB gy o l o e G DEMO
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a a Roc lebr ente z Cu m e e l u ng S. C omí a A. D arcí Mª iz G u R . A. B
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GLO BAL
THINKERS
Indenxowledge of the course Basic k
The scientific method 1. 2. 3. 4.
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The scientific method Research in the laboratory Research in the natural environment Search for information
CHALLENGES THAT LEAVE THEIR MARK
The biodiversity in your fridge .................................................. 26
1 Living beings • 1. 2. 3. 4. 5. 6.
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Lynn Margulis. An exceptional biologist Our planet and conditions for life on Earth What is life on Earth made of? Cells: the building blocks of life Vital functions The classification of living beings The five kingdoms
Understand, reflect on your learning an test yourself
2 Monera, Protists and fungi • 1. 2. 3. 4.
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Alexander Fleming. A careful observer Kingdom Monera Kingdom protoctista: Protozoa Kingdom Protoctista: Algae Kingdom Fungi
Understand, reflect on your learning an test yourself
3 Plants • 1. 2. 3. 4. 5. 6.
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Margaret Agnes Chase. A botanist and activist Kingdom Plantae The classification of plants Vital functions in plants: nutrition Vital functions in plants: interaction Vital functions in plants: reproduction Plants, humans and the environment
Understand, reflect on your learning an test yourself
Portfolio .............................................................................................. 84
CHALLENGES THAT LEAVE THEIR MARK
CHALLENGES THAT LEAVE THEIR MARK
Spotting fake news ......................................................................... 86
Ecological imprint of my mobile phone ............................... 150
4 Animals. Vital functions
7 Ecosystems
• 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.
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Joan Beaucham Procter. An intrepid herpetologist The animal kingdom Nutrition in animals Interaction animals Reproduction in animals Poriferans, cnidarians and worms Molluscs and echinoderms Arthropods Fish and amphibians Reptiles and birds Mammals Animals, the human being and the environment
• 1. 2. 3. 4. 5. 6. 7.
Understand, reflect on your learning an test yourself
8 Ecosystems and human beings
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Rachel Carson. Speaking for the environment The Earth’s atmosphere The atmosphere and living beings Air pollution and its consequences Water and living beings Where is the Earth’s water? The water cycle Uses of water and sustainable water management
Understand, reflect on your learning an test yourself
6 The geosphere: rocks and minerals • 1. 2. 3. 4.
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• Jacques-Yves Cousteau. A window to the underwater world 1. What is an ecosystem? 2. Abiotic factors 3. Biotic interactions 4. Trophic levels 5. Food chains and webs 6. Terrestrial ecosystems: Biomes 7. Aquatic ecosystems 8. Soil as an ecosystem
Understand, reflect on your learning an test yourself
5 The atmosphere and the hydrosphere
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Georgius Agricola. The doctor who studied mining The Earth and its geosphere Components of the geosphere: minerals Components of the geosphere: rocks Geosphere resources and humans
Understand, reflect on your learning an test yourself
Portfolio ............................................................................................ 148
• 1. 2. 3.
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Wangari Maathai. The activist: trees, justice and peace We use ecosystems We change ecosystems We protect ecosystems
Understand, reflect on your learning an test yourself
We explore our ecosystems
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1. Examples of aquatic ecosystems 2. Examples of natural terrestrial ecosystems 3. Examples of human terrestrial ecosystems
Portfolio ........................................................................................... 206
1
LIVING BEINGS
LYNN MARGULIS
An exceptional biologist If you hear the word ‘microorganism’, what do you think of? Lots of people only associate them with danger and illness, but for me they’re much more than that. They’re life itself! Let’s take bacteria as an example. They have existed for a very long time, they are incredibly varied and they have colonised all possible environments. I bet you won’t believe me if I tell you that I carry photos of bacteria in my purse, next to the photos of my children! My name is Lynn Margulis. I was born in 1938, in Chicago, in the USA. When I was only 16 I started university. I was fascinated by living beings and wanted to study Biology. When I graduated, I decided to become a 28
teacher and help others to learn about the work that scientists do. As a scientific researcher, I dedicated a great part of my life to the study of microbes. I was even the author of a revolutionary theory: the theory of endosymbiosis. Also, together with my colleague Karlene V. Schwartz, I proposed a modification to the classification of living beings into the five kingdoms. Thanks to us, protozoa and unicellular and multicellular algae became known as Kingdom Protoctista. My friends have described me as a short, restless woman who is curious about everything, and I think that’s a very good summary!
GES THAT
CHALLEN
EIR LEAVE TH
LANGUAGE BANK SPEAKING
1 Play a guessing game in small groups. Follow the instructions. Step 1: T ake it in turns to think of a living being – but don’t tell anyone what it is! Step 2: Ask the person whose turn it is questions to discover which living being they’re thinking of. Step 3: C an you guess what it is? Now it’s your turn to think of a living being.
2 Lynn Margulis once said ‘Life did not take over the world by combat, but by networking.’ What do you think she means?
MARK
LEARNING SEQUENCE MY FRIDGE. A WHOLE NEW WORLD TO EXPLORE 1.1
Study the environmental conditions of the research area, such as temperature, relative humidity, light, etc. In this case it is the inside of the fridge. Compare it to somewhere on planet Earth.
1.2 Choose an item in the ecosystem and analyse the nutritional information listed. 1.3 Find information about the components of your favourite item of fresh food. 1.4 The secret life of your fridge. Grow mould in two petri dishes. Put the lid on one of them and put it inside your fridge. Leave the dish without a lid outside the fridge for a few days. Have a look at the contents of the dishes under a microscope. You’ll see a lot more living beings than with your naked eye. 1.5 Get some plant tissue (from an onion) and animal tissue (formed by epithelial cells) from your fridge. Stain both specimens and look at them under the microscope.
WRITING
A newspaper article
3 You have been asked to write a short article about the work of microbiologists for your school newspaper. Do research and include the information below.
• What do microbiologists do? • What qualifications do they have? • Where do they work? • What is a typical day like for a microbiologist?
CLASSIFIYING THE LIVING THINGS IN MY FRIDGE 2.1 Classify the fresh food in your fridge into the five kingdoms. Think about the kingdoms or groups of living beings that you can’t find. Which items of food might contain them? Think about why they aren’t in your fridge. 2.2 Analyse the biodiversity of all the fridges in the class. Which species are most common and which are less common? 2.3 Find the scientific names for your favourite fresh foods. + for guidelines, go to anayaeducacion.es 29
1
OUR PLANET AND CONDITIONS FOR LIFE ON EARTH
There are eight planets in our Solar System and we live on the planet Earth. The Earth orbits the Sun, which is one of the hundreds of thousands of millions of stars that form our galaxy, known as the Milky Way.
1.1 The Earth The Earth is a solid planet mainly made up of rocks. It is surrounded by a layer of gases and also has liquid water on its surface. It is the only planet in our Solar System that contains life. The four things mentioned above, that is, rocks, gases, liquid water and life, correspond to the Earth’s four different layers or ‘spheres’ and how they interact with each other.
The Earth is divided into four layers or ‘spheres’ that constantly interact with each other: the biosphere, the atmosphere, the hydrosphere and the geosphere.
The Earth’s different layers The atmosphere A layer of gases surrounding the Earth
The hydrosphere
The biosphere
All of the liquid water on the Earth
All the living beings inhabiting the Earth
The geosphere The solid base made up of rocks and minerals
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UNIT
1
1.2 The conditions neccesary for life The Earth is the only planet in our Solar System that contains living beings. Life on Earth is able to exist only because of the conditions found here, which is not the case for any other planet near to ours.
• The distance between the Earth and the Sun is ideal for life to exist. Solar radiation produces light and heat. If we were closer to the Sun, there would be too much solar radiation. If we were further away, there would be too little.
• The atmosphere protects the Earth from some solar radiation that is harmful to life and it also helps to keep our planet warm. It also contains two gases, namely oxygen and carbon dioxide, which we need for respiration and which plants need for photosynthesis.
• The average temperature on Earth is 15 °C, which makes it possible for liquid water to exist. Liquid water is essential for both living beings and their environments. The Sun’s energy makes it possible for liquid water to change states (for example, liquid to solid or liquid to water vapour). It causes liquid water to evaporate, which is then recycled in the clouds and, as a result of gravity, eventually falls back down to the Earth. This process occurs constantly and is known as the water cycle.
Focus on English Bio- is a combining form which literally means life. It comes from the Greek bíos (life). Biology, biodiversity and biosphere are compound words which use this combining form. This will help you to understand better what they mean. Bio- is used to indicate a human life or career: biography, biopic.
Life could no longer exist
All the liquid water would evaporate from our atmosphere and hydrosphere.
• The Earth’s climate is also less hostile because we have seasons and there is a quick change between day and night.
There would be widespread drought.
The poles would melt.
A good place to live The What if? Our planet’s location relative to the Sun makes it possible for life to exist on Earth. However, if the Earth was closer to the Sun, or further away, or if the conditions of the Earth’s atmosphere changed, life on our planet would be different. The diagram on the right shows what would happen if the Earth was closer to the Sun. Look at it carefully and apply the same thinking tool to each of the following cases (go to the resource bank at anayaeducacion.es for more information on how to apply this thinking tool). a) What would happen if the Earth was a little further away from the Sun? b) Look for information about the gases that form part of the atmosphere. Which of them are essential for life? What would happen if the composition of the atmosphere changed? For example, if the concentration of carbon dioxide increased, how would this affect life on Earth? c) What is the habitable zone of a star? Investigate and name the criteria that make a planet habitable or inhabitable. Then invent a star with a planet in its habitable zone and describe the characteristics of the planet.
The temperature would increase.
What would happen if the Earth was closer to the Sun?
The Earth would orbit closer to the Sun.
Gravity on the Earth would change.
A different orbit would change the seasons.
Life could no longer exist. 31
2
WHAT IS LIFE ON EARTH MADE OF?
As you already know, the biosphere consists of all the living beings that inhabit the Earth. All living beings have three things in common which enable us to distinguish them from non-living beings:
• All living beings are made up of the same kind of substances: organic and inorganic substances.
• They are all made up of similar units: cells. • They perform three vital functions: nutrition, interaction and reproduction.
2.1 The chemical composition of life Inorganic substances
Everything in the universe is made up of tiny units called atoms. Oxygen and hydrogen are examples of different kinds of atoms. Atoms join together to form different substances. For example, two hydrogen atoms join together with one oxygen atom and form a water molecule.
Oxygen atom
Living beings are made up of two kinds of substances:
• Inorganic substances, which can be found in both living and
Hydrogen atoms
non-living beings. Examples include liquid water and mineral salts.
Water molecules are made up of two hydrogen atoms and one oxygen atom. Chlorine atom
Sodium atom
• Organic substances or biomolecules, which are exclusively found in living beings. Examples include carbohydrates, lipids, proteins and nucleic acids.
2.2 Inorganic substances Liquid water Liquid water is an essential component for living beings. In fact, 70 % of living matter is made up of liquid water. Liquid water also plays a key role in most transformations that happen inside cells.
Mineral salts Mineral salts help to regulate many vital processes. They also have a structural function in the skeletons of living beings.
Sodium chloride, commonly known as salt, is made up of chlorine and sodium atoms. In its solid state, this salt forms a crystalline structure, which means it is organised like in the picture. However, when it is in an aqueous solution, the bonds between the ions (positive and negative atoms) dissociate.
Understand, think, search... 1 Name the three things that all living beings have in common. 2 What are the main components of all living beings? 3 Explain why carbohydrates, lipids, proteins and nucleic acids are called biomolecules.
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UNIT
2.3 Organic substances
1
Look at the following molecules
Carbohydrates Carbohydrates are a type of biomolecule that provide cells with energy. They also form part of some cell structures, such as the cell wall, which you will study in this unit.
Lipids Lipids are molecules that contain a lot of energy. Cells use them to store energy. They also provide heat insulation and form part of certain cell structures, such as the plasma membrane, which you will study in this unit.
Glucose molecule (carbohydrate)
Proteins Living beings contain billions of protein molecules. Proteins are essential for many different functions. For example, they help us to contract our muscles.
Fatty acid molecule (lipid)
Nucleic acids Nucleic acids are relatively large molecules. In fact, DNA (deoxyribonucleic acid), which contains vital information that organisms need to function, is an example of a nucleic acid.
Understand, think, search... 4 Look at the information about the chemical composition of a human being. a) Calculate the percentages of organic substances and inorganic substances in this living being.
Protein macromolecule
b) Which biomolecules provide living beings with energy?
Lipids 9%
Carbohydrates 4 % Mineral salts 1%
Protein 16 % Water 70 %
Nucleic acid macromolecule
a) Look at the glucose and fatty acid molecules in the picture. The black spheres represent carbon, while the white ones represent hydrogen and the red ones represent oxygen. How many carbon, hydrogen and oxygen molecules are there in each of these substances? b)
Thinking hats. Proteins and nucleic acids are macromolecules. In other words, they are molecules with very complex structures. Do some research to find out about the structure of these molecules. What are they made up of?
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3
CELLS: THE BUILDING BLOCKS OF LIFE
3.1 What are cells like? Biomolecules group together to form more complex structures inside cells. These structures enable cells to perform their functions. In general, cells are microscopic in size, so we cannot see them with the naked eye. As a result, we could not study them until microscopes were invented and further developed. All cells are made up of the following fundamental components:
• The plasma membrane, which is a thin layer that protects the cell. It regulates the exchange of substances coming in and out of the cell from the surrounding environment.
• The cytoplasm, which is a kind of liquid that fills the inside of the cell. It contains many different substances and cell components.
• Genetic material, which is made up of DNA fibres. This contains all the information needed to control cell functions and can be passed on to the next generation of daughter cells during reproduction.
• Organelles, which are small structures that specialise in performing specific functions. Not all organelles are found in all the different types of cells.
Prokaryotic cell
3.2 Types of cells
Cell wall Plasma membrane
There are two different types of cells. These are prokaryotic and eukaryotic cells.
Prokaryotic cells
Genetic material (DNA)
Prokaryotic cells do not have a nucleus. As a result, the DNA found in these cells is contained in the cytoplasm. They have a cell wall and just one type of organelle known as a ribosome, whose task is to synthesise proteins. They may have flagella, which are a kind of filament that helps the cell to move.
Understand, think, search... 1 How do we classify cells as prokaryotic or eukaryotic? 2 Which cellular structures are being defined in the phrases below? a) This contains mainly water and dissolved substances. b) This structure forms a boundary around the cell. Cytoplasm Ribosomes
Flagella
c) This controls cellular activity.
3
Using a search engine, look for three images of prokaryotic cells taken under an electron microscope. a) Draw the shape of them in your notebook and label the structures you identify. b) Which structures have you identified? Which are present in all the prokaryotic cells you found? Which are not present? What is the function of each structure?
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UNIT
1
Eukaryotic cells Eukaryotic cells are more complex than prokaryotic cells. The DNA they contain is surrounded by a membrane, which forms the nucleus. They have a plasma membrane and cytoplasm, which contain many different types of organelles, as well as ribosomes. Mitochondria are an example of this type of organelle. They are specialised in generating energy. Most living beings are made up of eukaryotic cells. There are two different types of eukaryotic cells:
• Eukaryotic animal cells, found in animals and certain unicellular organisms such as protozoa, which you will study later on.
• Eukaryotic plant cells, which are found in plants and algae. They have a cell wall and organelles that can only be found in plants. For example, organelles specific to plant cells include chloroplasts, which are specialised in photosynthesis. Large vacuoles are used to store substances.
Eukaryotic animal cell Nucleus
Understand, think, search... 4
The mirror. Look at the images of the eukaryotic plant cell and the eukaryotic animal cell, then copy the following chart into your notebook and fill it in (learn more about this tool at anayaeducacion.es).
Eukaryotic animal cell
Eukaryotic plant cell
Distinguishing characteristics
Similarities
Distinguishing characteristics
?
?
?
?
?
?
?
?
?
Eukaryotic plant cell Plasma membrane
Nucleus
Cell wall Plasma membrane
Genetic material (DNA) Mitochondria
Genetic material (DNA)
Chloroplast
Cytoplasm
Cytoplasm Mitochondria Ribosomes
Vacuole
Ribosomes
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3
CELLS: THE BUILDING BLOCKS OF LIFE
3.3 Cell size Cells* vary greatly in size. Nevertheless, most cells are microscopic. This means that they cannot be seen with the naked eye. We use a microscope to see them. Cells are measured in units of length known as micrometres (μm).
Focus on English
One micrometre is one thousandth of a millimetre.
When Robert Hooke looked through a microscope at a thin piece of cork, he saw a series of walled boxes. They reminded him of the small rooms, called cells, that monks lived in. Nowadays, cell is more commonly used as a name for a different type of room; a prison cell.
1 μm = 0.001 mm 1000 μm = 1 mm Bacteria are the smallest kind of cell. In general, they measure between 1 and 2 micrometres in length. Animal cells vary greatly in size. For example, red blood cells measure 7 micrometres, cells in the liver measure 20 micrometres, sperm cells measure 53 micrometres and egg cells (ovum) measure 150 micrometres. Plant cells vary between 10 and 100 micrometres in length. Some cells in the plant’s epidermis can almost be seen without a microscope!
Analyse these microscopy images 0,2 μm
15 μm
10 μm
The photos show what cells look like under different microscopes. Look at them and answer the following questions. a) Calculate the true size of the cell by using the scale above each image. b) What kind of cells are they? How do you know? c) Draw a diagram of each cell in your notebook and label the structures you know.
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3.4 Cell shape In addition to having different sizes, cells also have different shapes. Cells can be round, cylindrical, spindle-shaped (fusiform), prismatic, flat or star-shaped. There are other shapes too. The shape of a cell is determined by its function. For example, red blood cells are biconcave in shape, like discs with a flattened centre. This allows them to carry as much oxygen as possible. Neurons are star-shaped with branches that allow them to communicate with one another. Muscle cells are long, to allow them to contract. The cells covering our organs are usually cube or prism shaped.
Visual art
Create A cells mosaic. Mosaics are a type of work of art made of pieces (called tesserae) of different materials. In the same way as tesserae in a mosaic, cells join together to form tissues and organs. Let’s make a cells mosaic!
Different cell shapes
Spermatozoon (sperm cell)
Adipocyte (fat cell)
Ovum (egg cell)
Muscle cell
Hepatocyte (liver cell) Cone cell
Pigment cell
Red blood cells
Neuron
Epithelial cells
a) Look at the cells in the picture above. Describe the shape of each one. b) Choose four cells. Find out what their function is. Try to link their shape to the functions they carry out. c) The cells in the picture are not to scale. This means that they are not the same size as in real life. Find out the true size of the cells you picked for question b. Then, put them in order from the smallest to the largest.
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4
VITAL FUNCTIONS
Living beings perform three vital functions. These are fundamental processes that must be carried out in order to sustain life.
4.1 Nutrition Nutrition is the vital function through which living beings obtain the matter and energy they need to survive, using the following processes:
Think about the roles of nutrition Autotrophic nutrition Inorganic nutrients are taken in and used to produce organic nutrients.
The Sun’s energy
Inorganic nutrients
Oxygen Carbon dioxide
Organic nutrients
Carbon dioxide Oxygen
Obtaining nutrients Nutrients can be organic or inorganic. Nutrients are substances that living beings take in. They are used by cells to perform their functions. There are two types of nutrition:
• Autotrophic nutrition means that inorganic substances are taken in and used to synthesise organic nutrients. Examples of inorganic substances include carbon dioxide and the Sun’s energy. This process is known as photosynthesis.
• Heterotrophic nutrition means that organic matter from other living beings is consumed in order to produce organic nutrients and energy.
Liquid water and mineral salts
Respiration
Heterotrophic nutrition Organic nutrients are obtained through food.
Organic nutrients
Carbon dioxide
Transporting substances
Oxygen
Food
Both of the pictures have blue labels naming specific compounds. Which process are these compounds used in? Why are the compounds the same in both pictures?
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All living beings take in oxygen (O2) and expel carbon dioxide (CO2) in a process we call respiration. Respiration takes place inside our cells within the mitochondria. In the presence of oxygen (O2) complex molecules are converted into liquid water and carbon dioxide (CO2), which is then released from the cell. This process also generates energy, which cells use to synthesise their components and carry out their functions.
Substances pass in and out of unicellular organisms through the plasma membrane. Multicellular organisms do not come into direct contact with the external environment. Instead, they use specific mechanisms for absorbing, transporting and eliminating substances.
Cellular excretion Excretion is the process of eliminating waste substances, such as CO2 and liquid water. Other substances produced during cellular activity are also eliminated.
UNIT
4.2 Interaction
Interaction When it is hot, dogs react by sticking their tongues out and panting in order to regulate their body temperature.
Interaction is the vital function through which living beings respond to internal or external changes. It can be broken down into three different stages: Detecting stimuli: receptors Stimuli are the changes that occur in an organism’s internal or external environment and can be perceived by living beings. Living beings are able to detect certain stimuli, such as light, heat and movement, with their receptors.
1
Some plants react to light by turning their flowers towards it.
Types of reproduction Asexual reproduction
Preparing a response: coordination Living beings process the information from the receptors and decide how to respond through a series of processes known as coordination. Coordination can take place within one cell or it can be carried out by complex systems made up of specialised tissues and organs.
Responding: effectors The response prepared during the coordination stage is then carried out by specialist cells called effectors. These effectors produce movement, substances and changes in body’s shape or function, amongst other things.
4.3 Reproduction Reproduction is the vital function carried out by living beings to create new living beings that are either identical or similar to them. It guarantees species survival. There are two types of reproduction: asexual and sexual. Asexual reproduction Asexual reproduction refers to one single parent (progenitor) producing a copy of itself, by itself. This copy is identical to the progenitor.
Sexual reproduction Sexual reproduction involves one male and one female progenitor. Together, they produce a descendant that is similar to them. Specialised reproductive cells known as gametes are necessary for this process.
Parent cell (progenitor) Sexual reproduction Male and female gametes come together to create a new living being, which has characteristics that are similar to both progenitors. Female gamete
Daughter cells (descendants), which are identical to the parent
Male gametes
Imagine if you could choose a mode of reproduction depending on the conditions Some organisms can choose to reproduce asexually or sexually, depending on the conditions. Think about what those conditions could be and answer the questions: • What are the advantages of each process? •W hy do you think an organism may choose to reproduce in one way or the other? •F ind out what parthenogenesis is and write a brief text to explain it. • I f humans were parthenogenetic organisms, how do you think we would reproduce?
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5
THE CLASSIFICATION OF LIVING BEINGS Carl Linnaeus (1707-1778)
There are many different types of living beings. We use specific criteria to classify them into groups. This helps us to identify them more easily and to study them better. The criteria used to separate them into different groups must be a natural trait.
5.1 Taxonomy Taxonomy is the science of classifying living beings. In the 18 th century, the Swedish botanist Carl Linnaeus began to group living beings together by looking for common characteristics. He organised them into different taxonomic ranks called taxa.
Taxa are groups used to classify living beings. There are seven different taxa, namely: kingdom, phylum, class, order, family, genus and species.
The broadest taxon is called kingdom. Each kingdom groups many different living beings together based on the few characteristics they have in common. The narrowest taxon is called species. Each species is a group of living beings that are so similar they are capable of reproducing with one another to produce fertile descendants. The diagram shows the different taxa.
Carl Linnaeus is often referred to as the father of taxonomy. Taxonomy is a hierarchical system used to classify living beings into different groups. An organism included in a broader taxon may also appear in the taxon below it. Changes have been introduced ever since Linnaeus first introduced the classification method. Nevertheless, even today, the main principles are still the same.
Understand, think, search... 1 What is a species? 2 Many of the names we commonly use to refer to living beings do not correspond to a specific species. They often refer to groups of species corresponding to higherlevel taxa. Which taxa do the following common names refer to: beetle, insect, ant, giraffe?
3
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Find out the scientific name for: the holm oak, the Iberian lynx, and the dog rose.
The plant kingdom includes anything from the oak tree to the common fern. The animal kingdom includes living beings from tiny fish to giraffes! Each time we move down a taxon, the living beings included in each group become more similar to one another. This finally brings us to species.
5.2 Binomial nomenclature Linnaeus also introduced binomial nomenclature, where a Latin name was given to all living beings. This name is usually written in italics and consists of two words. The first word, beginning with a capital letter, is the generic name and it identifies the genus. The second word, which is always written in lower case, is the specific name and is used only to refer to that specific species. Together, both words form the scientific name. For example, the scientific name for a sparrow is Passer domesticus.
Classifying an unusual species Taxonomists have sometimes found organisms that are difficult to classify. Imagine you have discovered an unusual species and you want to classify it in a table like the one on the right-hand page. Invent a new species choosing any characteristics you like, then draw it. To help you, first choose a kingdom and a phylum, then invent the names of the taxa and the organisms that belong to it until you get to your species.
UNIT
1
An example of plant and animal taxonomy
Kingdom
Plants
Animals
Phylum
Angiosperms
Dicotyledons
Asterales
Pseudanthiums
Bellis
Bellis perennis
Arthropods
Class
Insects
Order
Beetles
Family
Scarabaeidae
Genus
Species
Copris
Copris hispanus
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6
THE FIVE KINGDOMS
6.1 The organisation of living beings Living beings can be unicellular or multicellular.
• Unicellular organisms are made up of just one single cell that carries out all the vital functions. They can be prokaryotic or eukaryotic cells.
• Multicellular organisms are made up of more than one cell and are always eukaryotic. Most of the time, the cells in multicellular organisms join together to form: – Tissues, which are groups of specialist cells that carry out the same function. – Organs, which are groups of different tissues, designed to carry out a broader function. – Systems, which are made up of different organs and carry out a more complex process.
Levels of organisation in plants
Levels of organisation in animals
form
Cells
form
Cells
which form
which form Tissues
Tissues
which form which form Organs Organs
Living beings
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Systems within the living being
UNIT
1
6.2 The five kingdoms Organisms are organised into five main groups, based on factors such as:
• Cell type. Organisms can be prokaryotic or eukaryotic. • Number of cells. Organisms can be unicellular or multicellular. • Whether or not they have tissues • The type of nutrition performed. Organisms can either be
Analysing the five kingdoms Use the picture to answer the following questions: a) Which kingdoms autotrophs?
include
autotrophs or heterotrophs.
b) Which kingdoms include unicellular organisms?
These criteria are used to divide living beings into five different kingdoms: Kingdom Monera, Kingdom Protoctista, Kingdom Fungi, Kingdom Plantae and Kingdom Animalia.
c) Which kingdoms include organisms with tissues? d) Which kingdoms include organisms with tissues, organs and systems?
Kingdom Monera Unicellular, prokaryotic organisms which can be either autotrophs or heterotrophs. They sometimes form colonies. Kingdom Protoctista Organisms in this group are made up of eukaryotic cells. They may be made up of one cell (for example, protozoa and microscopic alga) or may be multicellular but not form tissues (for example, larger algae). Protozoa are heterotrophic organisms. Algae are autotrophic organisms. Kingdom Fungi Organisms in this group are made up of eukaryotic cells. They are heterotrophic organisms. There are some unicellular varieties of fungi, for example yeast. Other types are multicellular but do not form tissues. Examples include mould and mushrooms. Kingdom Plantae Organisms in this group consist of eukaryotic cells, with a rigid cell wall and chloroplasts. They are multicellular, made up of tissues and almost always have organs. They are autotrophs.
Kingdom Animalia Organisms in this group are made up of eukaryotic cells. They are multicellular, form tissues and almost always have organs and systems. They are heterotrophic organisms.
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ES CHALLENG
THAT
ARK
IR M LEAVE THE UNDERSTAND
Interpreting pictures
Organising your ideas
3 Name the labelled structures. What type of cell is
1
In your notebook, fill in the spaces in the concept map and extend its branches. Go to the resource at anayaeducacion.es.
Nutrition
this? 1
? ?
4
Prokaryotic cell
? Formed by cells
?
?
?
Living beings Have the same composition
? ?
3
2
4 Look at the pictures below and answer the questions: A
C
D
F
Summarising 2 Use these points to write your own unit summary: • What makes life possible on our planet? • What do all living beings have in common? • What is the difference between autotrophic and
B
E
G
heterotrophic nutrition? And between sexual and asexual reproduction?
• What is the main difference between prokaryotic cells and eukaryotic cells?
• What is the main difference between eukaryotic animal cells and eukaryotic plant cells?
• What are the main taxa for classifying living beings?
• What is a species? Can you think of two examples? Give the scientific name and the common name.
• What are the five kingdoms of living beings? What are their main characteristics?
• What are:
b) Which living beings are unicellular and which are multicellular? c) Which ones form tissues and which ones don’t? Which ones have organs? Which have systems? d) What type of nutrition and reproduction does each living being use?
Applying your knowledge
a) The kingdoms with prokaryotic cells and the kingdoms with eukaryotic cells?
5 Are the following statements about cell components
b) The kingdoms with beings that have tissues and the kingdoms with beings that don’t have tissues?
a) Nucleic acids are the main source of cell energy.
c) The kingdoms with beings that only use autotrophic nutrition, the kingdoms with beings that only use heterotrophic nutrition, and the kingdoms with beings that use both types of nutrition? 44
a) What kingdom does each living being belong to?
true or false?
b) Proteins are important because of their structure and their regulatory functions. c) Lipids are carbohydrates that regulate cell activity. d) The genetic material of cells is composed mainly of nucleic acids.
UNIT
Remember to choose resources from this unit for your porfolio.
6 If 5 kg of animal mass contains approximately 10 000 000 million cells: a) How many millions of millions of cells are there in a human being with a mass of 55 kg?
1
Moving forward 10 Read this text and answer the questions: Some animals, like starfish and lizards, can regenerate amputated parts of their bodies.
b) How many millions of millions of cells are there in an elephant with a mass of 6 800 kg?
Human beings can’t regenerate an arm or a leg, but our bodies are constantly regenerating cells like those in our blood, our skin and our liver. But not all the cells in our bodies can regenerate; differentiated cells, for example, have lost the ability to make copies of themselves.
c) What is the approximate mass of one animal cell?
7 A protozoan measuring 110 micrometres was observed in a sample of pond water. a) If we put 1 320 similar protozoa in a line, how long would the line be? b) How many protozoa would you need to make a line measuring 250 metres?
Cells that can regenerate are called stem cells. Stem cells can multiply and transform into any type of cell in order to replace others that are damaged or old. They act as reserves for regenerating different parts of the body.
8 Are the these statements true or false? a) Fungi use solar energy to make their organic nutrients. b) Plants use solar energy to make their organic nutrients.
a) Can all the body’s cells regenerate? Give some examples to support your answer.
c) Plants don’t use energy from food because they use energy from sunlight.
b) Do you think it is possible to regenerate any tissue from stem cells?
d) All living beings extract the energy they need from organic nutrients.
c) Do some research and describe how stem cells are used.
9 Do the following words refer to a type of cell, tissue, organ or system? a) Lymphocyte
d) Neuron
b) Skin
e) Heart
c) Digestion
f) Circulatory
REFLECT ON YOUR LEARNING In this first unit you learned about the great biodiversity found in a fridge and you started to understand the relationship between living beings and the conditions necessary for life. To reflect on your learning, go to anayaeducacion.es, download the self-assessment worksheet and complete it. Topics
I understand this and could explain it to my classmates
I don’t fully understand this. I still have some doubts
I don’t understand I’m not sure this
I understand the relationship between living beings and the conditions in their environment.
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I can see cell structures under a microscope in a practical experiment.
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TEST YOURSELF Go to anayaeducacion.es and complete the self-assessment worksheet to test your competencies. 45
G L O S S A RY A Asexual reproduction A type of reproduction where a single living being can produce one or more offspring that are identical to it. Atmosphere The layer of gases surrounding the Earth. Atoms Tiny units that make up all the matter in the universe.
Cytoplasm The jelly-like fluid that fills the inside of a cell.
E Eukaryotic cell A type of cell in which the genetic material is contained in a nucleus surrounded by a membrane, and which consists of many different organelles.
Autotrophic nutrition A type of nutrition where living beings can produce their own nutrients from substances like water, minerals and carbon dioxide using energy from the Sun.
B Binomial nomenclature A system for assigning unique names to organisms. Linnaeus was the person who created it. The names are in Latin and consist of two words written in italics: the first word indicates the genus and the second word indicates the species. Biomolecules Substances that are unique to living beings. Biosphere The part of the Earth where all life exists.
C Carbohydrates Biomolecules that provide energy to a cell. Cell The most basic unit of a living being. A cell can perform the three vital functions.
G Genetic material A fibrous substance called DNA that controls cell function. Geosphere The solid layer of the Earth formed of rocks and minerals.
H Heterotrophic nutrition A type of nutrition where living beings get the nutrients they need from other living beings or their remains. Hydrosphere The part of the Earth formed of oceans, seas, rivers, lakes and other bodies and currents of water.
I Inorganic substances Substances that are present in living beings and non-living matter, for example water and mineral salts.
Cell organelles Small structures in a cell that are specialised to perform different functions.
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Interaction A vital function that allows living beings to receive information from their external environments or from within their bodies, and respond to that information appropriately to ensure their survival.
UNIT
L Lipids Biomolecules that perform various functions like energy storage and heat insulation. Some lipids form part of the plasma membrane of cells.
1
Prokaryotic cell A type of cell that lacks a nucleus, and in which the genetic material exists freely in the cytoplasm.
M Membrane A thin and flexible casing that surrounds a cell and regulates the exchange of substances with the outside. Micrometre or micron A unit of length equal to one millionth of a metre. Multicellular organisms Living beings formed of more than one cell.
N Nucleic acids Large biomolecules containing the information that organisms need to function. DNA is a nucleic acid.
Proteins Complex biomolecules that perform a variety of functions in living beings, like forming cell structures, defending the organism from microorganisms, and muscle contractions.
S Sexual reproduction A type of reproduction where two living beings, one male and one female, provide specialised cells called gametes, which combine to create one or more offspring that are similar to the parent organisms. Species A taxonomic group for classifying living beings, comprising individuals that are similar enough to be able to reproduce with one another and produce fertile offspring.
Nutrients Organic and inorganic substances that living beings eat and that are useful for their cells.
O Organs Parts of the body that are made up of different tissues and perform a specific function.
T Taxa The groups into which we classify living beings, that is, kingdom, phylum, class, order, family, genus and species. Tissues Groups of coordinated cells that are specialised to perform a particular function.
P Phylum A taxonomic group for classifying living beings, made up of life forms that share general characteristics. A phylum falls within a kingdom and is divided into classes. Examples of phyla are arthropods and molluscs.
U Unicellular organisms Living beings formed of a single cell. 47
2
S T S I T O R P , A R E N MO AND FUNGI
ALEXANDER FLEMING
A careful observer
We are taught to fear failure and avoid making mistakes. We are told to hide them and pretend they never happened. But that’s nonsense. It was precisely my so-called carelessness and mistakes that revolutionised medicine. My name is Alexander Fleming. I was born into a very poor family in Darvel, Scotland in 1881. My father died when I was a child, so when I was thirteen, I moved to London. One of my half-brothers was studying medicine there, so as soon as I could, I decided to follow in his footsteps and study medicine too.
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one of the Petri dishes where I was growing infectious bacteria. I noticed that the bacteria disappeared where the drops of mucus had fallen. I was intrigued, so I started experimenting with this phenomenon. That’s when I discovered lysozyme, one of the natural chemical weapons our body uses to fight infections.
I had to serve in the army after I finished my degree, and I was horrified to see many soldiers dying from infected wounds. I decided to specialise in bacterial infections to find a cure.
A few years later, in 1928, I was experimenting with a culture of Staphylococcus aureus bacteria when it was accidentally contaminated by mould from another experiment. To be honest, my laboratory was always a mess... Anyway, I was amazed to see that the mould killed the bacteria. Because of this incident I discovered penicillin, a substance that the mould produces naturally to defend itself. This became the first antibiotic used in medicine to treat bacterial infections.
In 1922 I made a great discovery because of a simple sneeze! Yes, I had a cold and drops of mucus fell on
So now you know. You can go a long way in science by keeping a careful eye on your ‘mistakes’.
GES THAT
CHALLEN
LANGUAGE BANK SPEAKING Although Rebecca Lancefield began her university studies in an area unrelated to science, she discovered her vocation for biology because of her roommate.
1
Think about what subject you like the most and explain why to your group. Which professions are connected to this subject?
2 In small groups create a poster showing one of the cells in this unit. Explain to the class the different parts of the cell and their uses.
WRITING
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LEARNING SEQUENCE WATER, A BIODIVERSE NUTRIENT 3.1 Carry out a simple experiment by comparing how tap water and water from a river change under different conditions. Pour tap water into four different containers and put a lid on them. Do the same with water from a river. Put a container of each in a place which gets no sunlight. Put two containers of each in a place which gets lots of hours of sunlight. Put the last two containers in the fridge. Leave them for a week, then look at them all under a microscope. Note down any differences you see. 3.2 The inadequate storage or treatment of water can lead to the growth of microorganisms. Many of these can cause diseases. Investigate these diseases and the living things that cause them and write down your findings.
Create a presentation Some microorganisms (bacteria, protists, and fungi), can cause diseases. Others are essential for many useful processes. For example, some bacteria make yoghurt, some algae make renewable fuel, and some fungi make bread. Many scientists use microorganisms in new, modern processes, such as plastic recycling. Microorganisms can help us achieve some of the United Nation’s (UN’s) sustainable development goals.
3
Find information about the UN’s sustainable development goals. Choose goal 2, 12 or 13. In small groups, search for information on a microorganism that can contribute to achieving that goal. Create a presentation to share with the class.
IN MY FRIDGE. YOGHURT, A MIX OF CULTURES! 4.1 Investigate the interaction of living beings in yoghurt and kefir. Make a list of the species of living beings and include the kingdom they belong to. Explain the benefits to humans of these interactions. Look under the microscope to find out which living things you can see.
+ for guidelines, go to anayaeducacion.es 49
1
KINGDOM MONERA
1.1 About monera Monera are prokaryotic, unicellular organisms that can be autotrophic or heterotrophic. The most abundant group of monera are bacteria, which are microscopic beings that can adapt to all environments (water, land and air) and to the insides of living beings. They are capable of resisting the most extreme temperatures, acidity levels, salinity levels, and so on.
Types of bacteria
A Monera cell A
Depending on their shape, bacteria are classified as cocci, bacilli, vibrios, spirilla or spirochaeta. B
• Cocci are spherical.
D
• Bacilli are rod-shaped. • Vibrios are comma-shaped. • Spirilla and spirochaeta have an elongated spiral shape.
Some types of bacteria
C
Cocci
Bacilli
Vibrios
Spirochaeta
E
1 The picture shows a typical bacterial cell. Think back to what you studied in the previous unit and write down the names of this life form’s structures in your notebook.
2 Explain what you think it means that bacteria are able to adapt to all environments.
3 Some
monera, such as cyanobacteria, perform photosynthesis. Remembering the simple cell structure of bacteria, which organelle or structure do you think is responsible for this process? Find out the answer and explain it in your notebook.
4 Calculate the volume of a coconut with a diameter of 1.5 microns. Remember that the volume of a sphere is 4·π·r3/3.
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UNIT
2
Vital functions of bacteria
• How they feed. Since bacteria do not have organelles like chloroplasts or mitochondria, all nutrition processes take place in the cytoplasm. There are autotrophic bacteria, which synthesise their own organic matter through photosynthesis, and heterotrophic bacteria, which feed on the organic matter of other living beings. – Saprophytic or decomposer bacteria feed on remains of organic matter in the environment. Soil bacteria are an example of these. – Symbiotic bacteria form mutually beneficial relationships with other living beings. These relationships are known as symbioses. The bacteria found in the intestine, which form the gut microbiota, are an example of symbiotic bacteria. – Parasitic bacteria obtain organic matter from organisms in which they live and cause harm. These bacteria cause diseases such as tuberculosis.
• How they interact. Some bacteria move around using their flagella, spiral bacteria twist, some move by spinning around on themselves, some slide over surfaces and others remain immobile. Normally, bacteria live alone, but sometimes they group together to form colonies.
• How
they reproduce. Bacteria reproduce asexually by binary fission. This means that they divide their single cell into two.
1.2 The importance of bacteria Bacteria are present in all environments and play an essential role for other living beings. Although some are harmful, the majority are helpful.
• Helpful bacteria. The bacteria found in our bodies help us to function properly. Decomposer bacteria are used in the treatment of sewage and waste, among other things. Photosynthetic bacteria oxygenate water and the atmosphere. Others known as fermentative bacteria are used to make cheese, yoghurt or vinegar.
• Harmful bacteria. Some bacteria can cause diseases such as tetanus and salmonellosis. Others contaminate food and spoil it.
Binary fission 1 T he bacterium grows to a sufficient size and makes a copy of its genetic material (DNA). 2 T he bacterium narrows in the middle and divides its contents.
3 T wo daughter cells are produced. Daughter cells
Focus on English to twist: to turn or bend a part of something. to spin: to turn yourself or something else around and around very quickly. to slide: to move quietly and smoothly, often while continuing to touch the surface you are moving over.
Elections in Kingdom Monera Bacteria belong to Kingdom Monera, where they are holding a general election very soon. In the bacteriocratic system of government there are three main parties: the Destroyer Party, which includes all the bacteria that are harmful to other living beings; the Bacteriocool Party, which includes all the bacteria that are beneficial to other organisms; and the Wishy-Washy Party, which includes bacteria that keep to themselves. Choose one of the political parties and complete the following tasks: •D o a demographic study and write down five groups or species of bacteria that would vote for your party. •C ome up with a campaign slogan and logo that represents the political aims of your chosen party. •C hoose a name for the leader of your party and write a speech explaining your primary goals.
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2
KINGDOM PROTOCTISTA: PROTOZOA
2.1 About protozoa
A protozoan cell Genetic material (DNA)
The kingdom Protoctista includes protozoa and algae, which are simple eukaryotic beings.
Plasma membrane
Protozoa are eukaryotic, unicellular and heterotrophic organisms. They live in aquatic environments, in moist earth or inside other living beings.
Nucleus
Types of protozoa Mitochondrion
Protozoa are classified according to four main groups:
• Ciliate protozoa, which have tiny motile (moving) filaments on their surface known as cilia.
• Flagellate protozoa, which have a single filament called a flagellum Cytoplasm Ribosomes
that they move like a whip.
• Rhizopod protozoa, which move or capture food by means of footlike projections of the cytoplasm known as pseudopods.
• Sporozoan protozoa, which are parasitic protozoa with a very Contractile vacuole
simple structure and no movement structures. They owe their name to the fact they form resistant structures or spores.
Some types of protozoa Cilia
Cilia
Paramecia get around by moving the cilia covering their surface.
Vorticellas live attached to a substrate by a stalk. They use cilia to capture food.
Flagellum Pseudopod
Amoebas move using pseudopods, also known as false feet.
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Flagellate protozoa have one or more flagella, which they wave in order to move around.
UNIT Vital functions of protozoa
• How they feed. Protozoa are heterotrophic. Some are parasitic, since they consume the organic matter of other living beings in which they live and cause disease; others feed on organic matter, bacteria and other Protoctista.
2
Asexual reproduction in protozoa In ciliates
• How they interact. Many protozoa are capable of moving to capture food, to flee or to withdraw from light; others are immobile.
• How they reproduce. Although some reproduce sexually through gametes, protozoa normally reproduce asexually. The cell duplicates its DNA and divides its contents into two daughter cells.
Daughter cells In flagellates
2.2 The importance of protozoa • Helpful protozoa. Some protozoa are very important in the treatment of sewage, since they feed on the decomposer bacteria that it contains. Others make up plankton, and serve as food for many aquatic organisms that are in turn eaten by humans.
Daughter cells In rhizopods
• Harmful protozoa. Some protozoa are parasitic and cause diseases such as malaria, which is spread by mosquito bites, or amebiasis, which is transmitted through water or contaminated food. Maths and Visual Arts
Create
Organise microorganims by size.
Understand, think, search...
Daughter cells In sporozoans
1 In your notebook, correct the sentences that are false. a) Protozoa are heterotrophic. b) All protozoa live seperately from other living beings. c) Protozoa cannot move around. d) Protozoa only reproduce asexually. e) Protozoa have a cell wall.
2
Ideas pool. Get into groups and explain what the consequences would be for humans if protozoa were to disappear.
3
anayaeducacion.es. Go to the resource ‘Diseases caused by protozoa’ in your resource bank and describe some measures for preventing these diseases.
Daughter cells
Look at the images and answer the following. a) The first three images show how binary fission takes place in three different types of protozoa. Describe the differences you can see between them. b)
The last image shows the reproduction process typical of sporozoans, which is known as multiple division or sporulation. Search for information about this type of reproduction and, using the image to help you, produce a description explaining how this division process takes place.
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3
KINGDOM PROTOCTISTA: ALGAE Structure of a unicellular alga Canal Plasma membrane
Genetic material (DNA)
Flagellum
Nucleus
3.1 About algae Algae are organisms that are eukaryotic, unicellular or multicellular (in which case they are not tissue-forming) and autotrophic. They live in aquatic environments. Algal cells have a cell wall and chloroplasts, which contain a pigment called chlorophyll.
Types of algae Depending on their cellular complexity, algae are unicellular, such as Euglena or Hydrurus; colony-forming, for example Volvox or Pandorina; or multicellular, for example sea lettuce or Gracilaria. In addition to chlorophyll, algae may have other pigments that give them a characteristic colour. Depending on the predominant pigment, they are classified as follows:
• Green algae, which predominantly contain chlorophyll. Cytoplasm Contractile vacuole Mitochondrion Chloroplast
• Red algae, which contain red pigments. • Brown algae, which contain orange pigments.
Ribosome Cell wall
Some types of algae Unicellular algae
Colonial algae
Structure of a multicellular alga Thallus structure. Group of non-tissue-forming cells. Phylloid
Multicellular algae
Red algae
Gas bladders Cauloid
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Rhizoid
Green algae
Brown algae
UNIT Vital functions of algae
• How they feed. Algae are autotrophic; in other
2
Asexual reproduction of a unicellular alga
words, they synthesise their own organic matter through photosynthesis.
• How they interact. Unicellular algae can live independently or together, forming colonies. Unicellular forms have flagella which they use to swim towards the light. Multicellular forms have structures for attaching themselves to rocks. This means they can resist the strength of waves. They also have structures for floating on the water’s surface.
Daughter cells
• How they reproduce. They can reproduce asexually by binary fission, by fragmentation (when a new individual is formed from a fragment of another) or through spores (specialised cells from which new algae are produced); and sexually, through gametes. Some multicellular algae alternate between sexual and asexual reproduction.
Sexual reproduction in algae
3.2 The importance of algae • Helpful
algae. Thanks to the process of photosynthesis, algae oxygenate the oceans and the atmosphere and consume large amounts of carbon dioxide. They also serve as food for protozoa and many aquatic organisms. Humans use them as food, as fertiliser in farming, and as a base for cattle feed. In addition, we can extract substances like agar from them, which is used as a food thickener and a growth medium for plants and bacteria in laboratories.
Sporophyte Zygote
Spores Germination
Female gametophyte Fertilisation Female gamete
Male gametophyte
• Harmful algae. Some algae cause what are known as ‘red tides’ when they accumulate at certain times of year. These algae produce toxins that can harm marine flora and fauna, and that can reach humans through contaminated fish.
Understand, think, search... 1 Explain the difference between multicellular algae and colonial algae if both are formed by a grouping of non-tissue-forming cells.
2
Imagine that algae suddenly disappeared from the waters of our planet. Explain what could happen to living beings, giving reasons for your answer.
Male gamete
Multicellular algae reproduce by a system known as alternation of generations. This means that the type of reproduction changes after every generation. A phase of sexual reproduction by gametes is followed by a phase of asexual reproduction by spores, and so on and so forth. The asexual phase of algae is associated with the sporophyte and the sexual phase with the gametophyte. Keeping this in mind, and using the illustration to help you, write an explanation of each step in your workbook.
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4
KINGDOM FUNGI
4.1 About fungi Fungi are organisms that are eukaryotic, unicellular or multicellular (in which case they are non-tissue-forming) and heterotrophic. They live in moist, warm places that are protected from the light.
Structure of a unicellular fungus Plasma membrane Mitochondrion
Nucleus Genetic material (DNA)
Cell wall
Ribosome
Structure of a mould
Cytoplasm
Spores
Reproductive structures (sporangia)
Fungi cells have a cell wall that is different from that of plant cells. In multicellular fungi, the cells join to form filament-like structures known as hyphae. Strands of hyphae join together to form the mycelium, or the body of a multicellular fungi.
Types of fungi There are many different types of fungi, for example:
• Unicellular fungi, like yeasts. • Multicellular fungi – Moulds. In these fungi, the mycelium has a cottonlike appearance. They often grow on food, skin or moist ground. – Mushroom-forming fungi. The mycelium is buried in the ground, and what we call a mushroom is actually the reproductive structure where spores are formed. These fungi grow in woods or meadows. Examples include the saffron milk cap and the Champignon mushroom.
Types of fungi Unicellular fungi The cells form filaments called hyphae
Structure of a mushroom-forming fungus Reproductive structures (or sporangia) Moulds Spores The strands of hyphae form the mycelium
Hypha
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Mushroom-forming fungi
UNIT Vital functions of fungi
• How they feed. All fungi are heterotrophic. Depending
2
Reproduction of a yeast
on how they consume organic matter, they may be saprophytic, parasitic or symbiotic.
Bud
An example of symbiosis may be seen in lichens, which are formed by a fungus and an alga; the fungus provides the moist environment that the alga needs in order to live, and the alga provides the food needed by the fungus.
• How
they interact. Unicellular fungi can live independently or grow on fruits, plants and so on. Many mushroom-forming fungi live attached to the ground.
• How they reproduce. Many yeasts reproduce by budding, where two daughter cells are formed with one developing as a bud on the other. Multicellular fungi reproduce through spores, which generate a new fungus when they germinate. In many fungi, the reproductive structure is the mushroom, which is where the spores are made; in such fungi, the mycelium (the fungus’ actual body) is buried underground.
Yeasts divide unequally by forming a bud or protrusion that separates from the cell.
Daughter cells
Reproduction of a mushroom fungus 3 Cap Gills
4.2 The importance of fungi
Spores
• Helpful fungi. Saprophytic fungi that live in the ground break down organic matter, forming humus, on which plants feed. Some mushrooms, such as truffles and saffron milk caps, are highly valued in gastronomy. Many moulds produce antibiotics and other drugs. Yeasts are used to make alcoholic drinks, and food such as bread.
• Harmful fungi. Parasitic fungi cause diseases in people, such as athlete’s foot and ringworm. Others infect plants and damage crops. The toxins from some mushrooms can be fatal when consumed by mistake.
Understand, think, search... 1 Explain what a hypha and the mycelium of a fungus are. 2
anayaeducacion.es Go to the resource titled ‘Lichens’ and answer the following questions: a) Which living beings are connected in this symbiotic relationship? b) What does each living being provide to the other? c) Where do they live? Lichen
2
Stalk
1 Mycelium
Look at the image that shows how a fungus with fruiting body reproduces and answer the questions below: a) Write captions to describe each stage of the reproduction process. b) In some autonomous communities, there are laws about picking wild mushrooms. For example, you are not allowed to collect them in buckets, plastic bags or other containers; you are asked to use a basket instead. Why do you think a basket is preferable for collecting wild mushrooms? c) Find information about poisonous mushrooms in Spain and write down the names of three of them. Describe what can happen if you eat them. d) Write another list with the names of at least three edible mushrooms. Choose one of them and write a recipe that includes them in the ingredients.
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ES CHALLENG
THAT
ARK
IR M LEAVE THE
Interpreting pictures
UNDERSTAND
3 Look at the following pictures and answer the
Organising your ideas In your notebook, fill in the empty spaces of the radial diagram below. Use the resource available at anayaeducacion.es to learn how to draw this type of diagram. Ciliates
1
?
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d Re ae g al
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Proto ct
An
The five Kingdoms
C
D
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? Fu n g i
imals
Protozoa
ra ne
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M o
Vibrios Cocci
A
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questions:
Moulds
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a) Classify each organism, kingdom it belongs to.
indicating
which
b) What method of nutrition do they use?
Plants
c) Do they move around? What cellular structures do they use to do so? d) Do they live alone or do they form colonies? e) Do any of them cause diseases in humans?
Summarising 2
Write your own unit summary based on the information below
• Explain how bacteria feed. • Describe the process of bacterial binary fission. • Explain how protozoa feed. • Describe the structures that allow some protozoa to move around.
f) How do they reproduce?
4 Name the structures marked with numbers in the following diagram of a multicellular fungus, and answer the questions: 1 2 4
• How are algae classified? • Explain how algae reproduce. • Explain how fungi interact. • Describe how bacteria, protozoa, algae and fungi
3
are helpful and harmful to humans.
• Specify: a) The main characteristics of monera. b) The main characteristics of protozoa. c) The main characteristics of algae. d) The main characteristics of fungi.
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a) What constitutes a fungus’ real body? Where is it found? b) Explain the process shown in the picture. c) What do you think happens if, when we pick mushrooms, we pull them up instead of cutting them off at the substrate level?
UNIT
Remember to choose resources from this unit for your porfolio.
Applying your knowledge
f) Since they perform photosynthesis, fungi live in dry, sunny places.
5 Indicate whether the following statements apply to
g) Fungi can cause diseases in humans, but never in plants.
saprophytic, symbiotic or parasitic bacteria: a) They obtain organic matter from other living beings, to which they cause harm. b) They feed on remains of organic matter in the environment. c) They form mutually beneficial relationships with other living beings.
6 Would it be possible to find algae in the depths of the ocean? Give reasons for your answer.
7 Plasmodium is the causative agent of malaria. This protozoan measures 10 micrometres and is transmitted through the bite of the Anopheles mosquito. If the mosquito’s stylet is 0.1 centimetres long, how many protozoa can it inject in one bite? (Remember, 1 micrometre = 0.0001 mm.)
2
Moving forward 9 Read the following text and answer the questions: Euglena are a remarkable form of unicellular algae. They have an ‘eye’, which is a photoreceptor that detects light, but they also have an incredible form of nutrition. Scientists call these types of organisms mixotrophs, as they are both heterotrophic and autotrophic. Euglena contain clorophyll, so they can perform photosynthesis, generating organic biomolecules from inorganic substances and sunlight. However, they can also feed on the organic matter of other living beings they capture. This is a great advantage for these tiny unicellular organisms.
8 Indicate whether the following sentences about algae and fungi are true or false, and write them out correctly in your workbook: a) All algae are multicellular and visible to the naked eye.
a) What method of nutrition do Euglena use? What does it involve?
b) Red algae do not have chlorophyll as a photosynthetic pigment.
b) In what conditions do Euglena advantage over other algae?
c) Freshwater algae do not exist; all algae are marine algae.
c)
d) All bacteria cause diseases. e) Algae only reproduce asexually.
have
an
Search for information about algae cultivation in heterotrophic conditions and explain its use for biofuel production.
REFLECT ON YOUR LEARNING In this second unit, you have learned more about the relationship between the conditions in a particular place and the living beings that evolve there. You have also discovered a lot of living things that you can’t see with the naked eye, and you’ve learned a few laboratory techniques used in microbiology. To reflect on your learning, go to anayaeducacion.es, download the self-assesment worksheet and complete it. Topics
I understand this and could explain it to my classmates
I can differentiate between different types of unicellular organisms and classify them …
I don’t fully understand this. I still have some doubts
I don’t understand I’m not sure this
…
…
…
…
…
…
…
…
TEST YOURSELF Go to anayaeducacion.es and complete the self-assessment worksheet to test your competencies.
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G L O S S A RY A Alternation of generations A system of reproduction where one phase involves sexual reproduction by gametes and the other phase involves asexual reproduction by spores.
Cilia Small motile filaments on the surface of some protozoa that beat to enable movement.
B Binary fission A type of asexual reproduction in unicellular organisms where the parent cell divides into two identical daughter cells.
Cilia
F Flagellum A long appendage extending from the plasma membrane of some cells, which they use like a whip in order to move.
Flagellum
Budding A type of asexual reproduction where two daughter cells form, with one developing as a bud on the other. Bud
Fragmentation A type of asexual reproduction where a new individual forms from a fragment of another.
H Hyphae Filamentous structures formed of groups of cells that make up the body of a multicellular fungus.
C
K
Chlorophyll A green substance that captures energy from the Sun and allows photosynthesis to take place. We find it in plants, some algae and some bacteria.
Kingdom Fungi A group of unicellular or multicellular living beings that are formed of eukaryotic cells, have no real tissues and use heterotrophic nutrition.
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UNIT Kingdom Monera Unicellular prokaryotic organisms that can be autotrophic or heterotrophic. Bacteria are the most representative organisms of this kingdom.
2
P Parasite An organism that lives off another organism of a different species, harming it but not killing it. Pseudopods Foot-like projections of the cytoplasm in some cells, which enable the cell to move or capture food.
Kingdom Protoctista A group of non-tissue-forming eukaryotic organisms that can be multicellular or unicellular. Some use autotrophic nutrition (algae) and others use heterotrophic nutrition (protozoa).
Pseudopods
S Saprophyte An organism that feeds on remains of decaying organic matter. Sporangia Reproductive organs containing spores. Spores Sporangia
M Mould A type of multicellular fungus in which the mycelium has a cottony appearance. Mycelium The body of a multicellular fungus formed by strands of hyphae.
Symbiosis A mutually beneficial relationship between two individuals of different species.
Y Yeast Unicellular fungi.
Mycelium
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