Living Things and 1 Their Life Processes
Chapter
Well, Ari, if you haven’t been drinking your milk, what have you been doing with it?
Naughty Ari has been giving
his milk to the plant!
Do you think the milk actually helped the plant to grow?
Biology
What’s In This Chapter?
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Living
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Non-living
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Life processes
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What Will I Learn? I will: 1. Know the life processes that humans and other animals undergo. 2. Understand that all animals need air, water and food to stay alive. 3. Know the life processes that plants undergo. 4. Be able to describe the differences between living and non-living things using my knowledge of life processes.
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What Are the Life Processes in Humans and Other Animals? My pet moves about a lot,
My pet loves to eat, just like me!
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Hmmm... Rita, Ari, their pets and all of us are alike in some ways. We carry out similar activities every day! What do you think these activities are?
The next time you visit a zoo, farm or national park, watch what the animals are doing. You may notice that some of the things they do are similar to the things you do! r
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Skills!
Observing, Communicating
Let’s do a show-and-tell! Bring a pet or its photo to school if you have one. Share with your friends what you have learnt and noticed about your pet. Here are some things you can share: • How long have you had your pet? • How do you take care of your pet? • Does your pet know you? How does it show that it recognises you? • What does your pet do if it hears a loud noise? • What is your pet’s favourite food? What does it do if it does not get enough food or water? • What does your pet do when it is tired? Now you have heard your friends share about their pets. What needs do the pets have in common? Do human babies have the same needs? 3
Biology
Just like humans, animals carry out activities every day. Most of these activities are necessary to keep living things alive. We call these activities life processes. Life processes include nutrition, movement, growth, sensitivity, respiration, excretion and reproduction.
Nutrition Living things need nutrition. Nutrition simply means eating! The food and water taken in by animals are converted into energy. Animals need energy to move and grow.
These giraffes get their food from the leaves of trees and water from streams or rivers.
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Movement Humans and other animals can move on their own. They require energy to move. Why is movement important? This bear has just caught a fish for lunch!
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This crab is hiding in a hole in the sand.
• Movement enables animals to look for shelter.
This mouse is running away from a cat. The cat wants to catch the mouse!
• Movement enables animals to look for food.
• Movement enables animals to escape from danger.
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Analysing, Communicating
Think about how you look for food, look for shelter and escape from danger in your daily life. Can you think of any other reasons why living things move? Discuss this with your friends.
ivity
This girl is reaching for a fruit on a tree.
Act >> Workbook
Activity 1: How Do I Survive? Activity 2: Move It! 5
Biology
Growth Nutrition helps living things to grow. When a living thing grows, it becomes larger in size. It also gains weight, which makes it heavier.
A baby horse, or a foal, grows into an adult horse. Ama ing
Facts!
The blue whale is the largest animal on Earth. It can grow up to 30 metres in length. It is also one of the ‘greediest’ animals. Blue whales feed on small sea creatures called krill. An adult blue whale eats about 3600 kg of krill a day!
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You will find out how some living things change in appearance in Stage 5 Chapter 2: The Life Cycles of Animals. 6
A child grows into an adult.
The appearance of a living thing may also change as it grows. Can you think of any animals like that?
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Sensitivity
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What would you do when something scares you? Imagine that you saw a cockroach unexpectedly. Would you scream or jump?
Try blowing at ants. Do you notice that they scurry away from you?
Living things are sensitive to changes around them. They respond to these changes. When a living thing makes a response, there is a change in its action or behaviour.
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What is the difference between respiration and breathing? Breathing is the process of inhaling and exhaling air. Respiration is the process of converting sugar into energy in your body. Find out more by doing an Internet search using words such as ‘Difference between respiration and breathing’.
Respiration If you cover your mouth with your hands and breathe on them like Rita on the right, your hands will feel warm. Where does your body get the energy to warm your hands? Your body gets its energy by making use of oxygen from the air you breathe in and sugar from the food you eat. Water and carbon dioxide are also produced as a result. This process is known as respiration. Animals use the energy to grow, repair their body and move. When you breathe in, you take in oxygen. This enables your body to convert sugar into energy. Respiration has taken place.
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Excretion Living things produce waste materials in their bodies. They get rid of these waste materials by passing them out of their bodies into the environment. This process is called excretion. Carbon dioxide and water are waste materials produced in the body. Carbon dioxide and water vapour are excreted when we breathe out.
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How are carbon dioxide and water produced in the body? Remember what you have learnt!
Our bodies also produce other waste materials. These are usually excreted from our bodies together with water as urine and sweat. If a living thing does not excrete, it will not be able to remove waste materials from its body. This will cause it to fall sick and eventually die.
What are the waste materials produced by these runners? How are these waste materials excreted?
Ama ing
Facts!
Many people think that passing out faeces (defecation) is a form of excretion. However, in Science, only the passing out of waste materials produced by the body is considered excretion. Faeces is food that is not digested (or absorbed) by your body. Hence, your body does not excrete the faeces.
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Ama ing
Reproduction Facts!
Humans usually produce only one young, or baby, at a time. However, sometimes two or more babies are born at the same time. Two babies born together to the same mother are called twins. Twins can look different or identical.
Reproduction is the process of producing a young from its parents. All living things will die one day. If one type of animal did not reproduce itself, soon there would be no more of its kind left. When this happens, we say that the animal has become extinct. When an animal reproduces itself, it gives birth to a young. The young will grow up to look like its parents. Some animals produce one young at a time.
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If you find it hard to remember the different life processes, Mrs Nerg can help you! You see, the letters in the name MRS NERG stand for the seven different life processes. Just take the first letter of each life process you have learnt, and you will find her! Meet Mrs Nerg and find out more about the seven life processes at Internet Link 1.1.
>> Workbook
Activity
Activity 3: The Toy Test
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Some animals produce many young at a time.
Some animals reproduce themselves by laying eggs.
Some animals reproduce themselves by giving birth to their young alive.
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What Are the Life Processes in Plants?
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Now you have learnt about the life processes in humans and other animals. Do you think plants undergo the same life processes? Let’s find out!
I water my plants so that they will grow
My mother tells me to eat my food so that I will grow bigger. Do plants need food and water to grow too?
Plants form another group of living things. Unlike humans and other animals, plants cannot move from one place to another. They do not need to find food like animals do. Finding and eating food are not necessary for plants because they can make their own food. However, plants also carry out life processes just like humans and other animals. Let’s take a closer look at the life processes in plants. 11
Biology
Look! I can make
No, you didn’t make your Nutrition own food. The ingredients Like humans and other animals, plants need food you are using came from
and water to survive. However, plants are different from humans and other animals — they can make their own food!
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You will find out more about how plants make food in Chapter 4: Introducing... Roots, Leaves, Stems and Flowers!
Plants use sunlight to make food. They contain a green pigment called chlorophyll, which is found mostly in the leaves. Chlorophyll traps energy from sunlight. The energy is then used to combine water and carbon dioxide to form sugar (food). Chlorophyll also gives leaves their green colour. What do you think will happen if plants do not get enough sunlight or water?
E xper imen t Tim e!
Observing, Analysing
Let’s find out what happens when plants do not get the water they need. Materials: • Two identical pots of green plants
• Measuring cup
Instructions: Step 1
Label the plants A and B. Place the pots in a sunny place. Step 2
Water Plant A with 30 cm3 (30 mℓ) of water every day for a week. Do not water Plant B. Step 3
Observe the plants after one week. 12
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E xper imen t Tim e!
Chapter
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Observing, Analysing
a. What happened to the plants? Record your observations below. Plant
Amount of water daily
A
30 cm3
B
0 cm3
Observations
b. What can you conclude from this experiment?
Experiment notes
In this experiment, we are testing what happens to plants when water is given or not given to them. So, we vary the amount So what variable would we of water given to the plants. We gave Plant A 30 cm3 of change if we wanted to find water daily, while Plant B was given no water. We kept out what happens if plants do all the other variables the same for both plants. not get sunlight? In Science, a variable is something that can be changed in an experiment. For example, in this experiment, where we place the plants, the size of the plants and the amount of water given to the plants are all variables. When only one variable is changed in an experiment, we call it a fair test. The variable we change is the variable we are testing.
Now I know that plants can make their own food! Hmmm... so did the milk I gave my plant earlier help it to grow?
Well, milk contains water, and plants need water to make food. So your milk
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Growth
Disco
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When a young plant begins to grow from a seed, we say that the seed has germinated.
When plants are able to make food, they will grow. When plants grow, they increase in size, height and weight. Here’s a picture of me when
Movement and sensitivity Do you think plants can move? Well, although plants cannot move from place to place like animals, they do move in other ways! Plants are sensitive to their surroundings. They respond to changes in their surroundings.
The leaves of plants grow towards light. That is why trees grow upwards.
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Act >> Workbook
Activity 4: Plant Senses!
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Roots grow (move) towards water. The roots of this tree grow deep into the soil to find water in the ground.
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Some plants are sensitive to touch.
The leaves of the Mimosa plant curl up if you touch them. That is why the plant is also called ‘touch-me-not’!
Fly trapped in the leaf
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Leaves have closed up
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Watch a video of flowers opening at Internet Link 1.2. Also, see a seedling growing towards light at Internet Link 1.3. These videos were actually recorded over many hours or even days. Why do you think such movement is important for plants? Discuss this with your friends. Observing, Analysing
The leaf of the Venus Flytrap snaps shut when a fly lands on it. The fly will be slowly digested by the plant!
Respiration and excretion Like animals, plants respire to get the energy they need. During respiration, plants take in oxygen and excrete carbon dioxide through tiny openings called stomata. Stomata are found mostly on the underside of leaves. Stomata
We can see stomata on the underside of leaves using a microscope.
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Biology
Reproduction Cross
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You will find out more about the plant parts in Chapter 4: Introducing... Roots, Leaves, Stems and Flowers!
Plants reproduce themselves to ensure that their kind does not become extinct. They do so in different ways. Most flowering plants (plants that produce flowers) reproduce using seeds. Their seeds are found in the fruits they produce.
Seed
Seedling Apple seeds grow into new plants.
Non-flowering plants, such as ferns and mosses, reproduce themselves from spores.
Spore bag
Spore
Underside of a fern Moss spore bags
Some plants reproduce themselves from other plant parts. New plants >> Workbook
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Activity 5: Plant or Animal? Activity 6: The Amazing Seed
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New plants may grow from the underground stems or leaves of some plants.
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How Can We Tell Living Things From Non-living Things? Look at my robot! After I wind it up, it can walk across
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Tom’s wind-up toy seems to be able to move on its own. Is it a living thing?
There are many things around us. We can classify them into two main groups, ‘living things’ and ‘non-living things’. How do you think living things are different from non-living things? We know that something is a living thing when it can carry out life processes, like nutrition, movement, growth, sensitivity, respiration, excretion and reproduction. A nonliving thing cannot carry out all of these life processes. The seven examples that follow explain the differences between living and non-living things. 17
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Nutrition All living things need food and water to stay alive, but non-living things do not.
A baby needs to be fed regularly.
A baby doll does not need food or water.
Growth All living things grow, but non-living things do not.
A living plant will grow bigger and taller over time.
A plastic plant will not change in size or height over time.
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Movement
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All living things things can move on their own, but non-living things cannot.
A horse can run.
A wooden rocking horse cannot move on its own.
Sensitivity All living things things can respond to changes around them, but non-living things cannot.
If only I could move...
A boy can respond to a change in the weather. Here, Ari is running for shelter to protect himself from the rain! A statue does not respond to a change in the weather. It cannot protect itself from the rain. 19
Biology
Respiration All living things can respire, but non-living things cannot. A man can respire to produce the energy he needs to lift heavy weights.
A figurine cannot respire to produce the energy to carry weights.
Excretion All living things can excrete, but non-living things cannot.
This boy is sweating.
Reproduction
This garden decoration does not sweat although it is under the hot sun.
All living things can reproduce themselves, but nonliving things cannot.
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A female lion can produce young.
A toy lion cannot produce young.
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Skills!
A candle flame can flicker. It seems to move on its own.
Clouds in the sky can move and grow bigger in size.
Discuss with your friends whether a candle flame and clouds are living things. Give reasons to support your opinion. Now think about a car. Which of the life processes does a car seem to have? How can you tell whether a car is a living thing or a non-living thing?
>> Workbook
Activity
Activity 7: Same But Different! Activity 8: A Diversity of Things Talk It Out
Can you remember what these new words mean? Pair up with a friend and test each other on these words! chlorophyll energy excretion extinct fern
flowering plant fruit growth life process moss
movement non-flowering plant nutrition reproduction respiration
respond seed sensitivity spore stomata
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Map It Out
Humans suc
Fire
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Other animals
Chair Living
Non-living
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Movement • To look for food and shelter, and escape from danger
Life processes
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Growth • To get bigger and heavier, and possibly change in appearance Reproduction • To produce young
Respiration • To release energy from food Sensitivity • To respond to changes
Battery-operated toy
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Plants
Nutrition • To convert food and
Excretion • To remove waste from the body
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Work It Out
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Comparing, Analysing
Let’s work out the following question together! Min has two cats, A and B. One of the cats is a stuffed toy.
Each cat was given 200 cm3 of water and 200 g of food. Study the information given in the table below and answer the questions that follow.
Day 1 Day 3 Day 5
Cat A Amount of Amount of 3 water left (cm ) food left (g) 200 200 200 200 200 200
Cat B Amount of Amount of 3 water left (cm ) food left (g) 200 200 160 140 100 110
a. Based on the information given in the table, which cat, A or B, is the stuffed toy? [1 mark] Cat A
Did you notice that the amount of food and water left decreased for Cat B but not Cat A? What does
b. How did you arrive at your answer in ‘a’? [2 marks] Living things need food and water to stay alive. As the amount of
food and water remained the same after five days for Cat A, [1 mark] it showed that the cat did not eat food or drink water. Thus, Cat A must be the stuffed toy. [1 mark] 23
Biology
Science @ Work
Environmental literacy
Life without plants at the bottom of the sea Far, far below the ocean’s surface, it is dark and freezing cold. Without sunlight, no plants can grow in there. Scientists used to think that no life could exist without plants to make food. Now, we are able to explore the world below using deep sea vehicles— and we find that it is actually full of life! In 1977, an underwater research vehicle called Alvin discovered hydrothermal (hot-water) vents on the ocean floor. Scientists found about 300 new species of animals living around these vents. These animals included giant clams and huge tube worms that grew up to over two metres in length! How can these animals survive without plants? Where did they get their food from? Alvin diving into the depths of the sea
Researchers found that tiny living things called bacteria in the water are able to make their own food from dissolved gases coming out from the vents. The tube worms and clams carried the bacteria in their bodies, so they could feed on the dissolved gases. The tube worms and clams were then eaten by other animals living on the ocean floor.
Some of the tube worms on the ocean floor were more than 250 years old! Scientists believe that the tube worms grow slowly and live longer because of their extreme living conditions.
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You will learn more about bacteria in Chapter 2: Sorting Living Things. 24