Unit 4 plants

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SCIENCE 5.

C.E.I.P. SANTA ANA (Madridejos)

UNIT 4. PLANTS.

CONTENTS: 1.– Characteristics of plants.

2.– Classification of plants: with flowers / without flowers.

3.– Parts of a plant: roots / stem / leaves / flowers.

4.– Vital functions of a plant: a .– Nutrition: Photosynthesis / respiration / transpiration. b.– Interaction. c.– Reproduction: c.1.– Sexual reproduction in plants with flowers: Pollination / fertilization / germination c.2.– Asexual reproduction in plants: Spores, stolons, bulbs…

5.– Uses of plants.

PLANTS are multicellular living beings with chlorophyll that can produce their own food (autotrophic nutrition), and they can’t move from the soil.

1.- CHARACTERISTICS OF PLANTS. 1.– Plants contain chlorophyll (that gives them their green colour) to produce their own food through the photosynthesis. So they have autotrophic nutrition.

2.- They can’t move from the soil.

3.- They are multicellular organisms with a nucleus.

The bonsai is a plant

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2.– CLASSIFICATION OF PLANTS:There are two groups: 1.- Plants without flowers: moss and fern.

2.– Plants with flowers: a.– Gymnosperms: naked seeds (pine) b.– Angiosperms: flower, seeds and fruit (apple) Moss

2.1.– Without flowers: like moss and fern (they reproduce them- 2 selves by spores).

Moss: are very small plants without real roots, stem or Sori with spores. leaves. They are fixed on rocks, soil and trees. They usually live in dark, cold and humid places…

Fern: are bigger plants. They have a stem what grows horizontally.

Fern They have roots to the soil and tall leaves. They like to live in the shade and in humid places. Under their leaves, they have sori to produce 3 spores.

2.2.– With flowers or seed plants: (grass, bushes, trees…) There are many plants in these group, but we can divide them on: a.- Gymnosperms: have ‘naked seeds’, and they are plants like conifers (pines, cypresses…) b.- Angiosperms: (flowering plants), they produce beautiful flowers 4 that later will transform into seeds protected by fruits.

(Gymnosperm) (Gymnosperm) pine pine tree tree

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USEFUL WORDS: .– chlorophyll .– autotrophic nutrition .– fern .– sori (sorus) .– seed plants .– gymnosperms

.– moss .– spores .– angiosperm

(Angiosperm) apple tree

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3.- PARTS OF A PLANT: All plants with flowers have the same structure.

THE PARTS OF A PLANT are: .– Roots: absorb water and nutrients. .– Stem: give support and transport nutrients. .– Leaves: make food (photosynthesis) .– Flowers: reproductive system of the plant.

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3.1.– ROOTS: is the part of the plant under the surface of soil. It fixes the plant to soil, and gets water and nutrients for the plant. There are different kinds of roots, but many of plants have a primary root (taproot) and many secondary roots with root hairs to absorb water and minerals.

3.2.- STEM: supports the rest of the plant (branches, leaves…) It also transport nutrients from roots to leaves through vessels.

There are two kinds of plants depending on their stems: a.- Woody plants: use wood as its structural tissue. They have a trunk. b.- Herbaceous plants: they don’t have woody stem, and they die at the end of season.

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3.3.- LEAVES: are green because of the chlorophyll, blade and they make food for the plant in the process of photosynthesis.. It has two parts: .- The petiole: links the leaf to the stem. petiole .– The blade: the main part of the leaf, with two sides (the upper side very bright and the lower side with some small openings called stomata to regulate the exchange of oxygen and water to the atmosphere.

There are evergreen plants that have leaves in all seasons, and deciduous plants that lose their leaves during Autumn.

stomata

midrib

vein

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3.4.– FLOWERS: are the reproductive organ of the plant.

Parts of the flower: .- All petals form the corolla to attract insects. .- All sepals form the calyx to protect the inner organs. .- The stamen is the male part of the flower and it’s formed by the anther (with pollen) and the filament. .- The pistil is the female part of the flower and it’s formed by stigma, style and ovary (with ovules that will become in seeds). .– roots .– leaves .– flowers .– anther .– style

.– root hairs .– petiole .– petals /corolla .– filament .– ovary

.- stem .– blade .– sepals/calyx .– pistil .– ovules

.– trunk .– stomata .– stamen .– stigma .– seeds

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4.- VITAL FUNCTIONS OF A PLANT: The vital functions are nutrition, interaction and reproduction.

A.– NUTRITION OF A PLANT: Plants have an autotrophic nutrition, so they make their own food. They obtain nutrients and water from the soil (xylem sap). They carry it to the leaves to transform into phloem sap (a fluid formed by water, sugars and minerals). Finally they carry it to the rest of the plant.

NUTRITION OF A PLANT: .– Photosynthesis: plants use water, CO2 and light, to obtain sugars and oxygen. .– Respiration: plants use oxygen and sugars to obtain energy, and expel CO2. .– Transpiration: plants expel water through stomatas in the leaves.

A.1.–PHOTOSYNTHESIS: It is the process used by plants to make their own food. They need water, minerals, carbon dioxide and sunlight.

Leaves have chlorophyll (that gives them their green colour). Leaves get water and minerals from roots, and carbon dioxide and sunlight to change them into sugars and oxygen. Sugar gives energy to the plant and oxygen is expelled to the air.

PHOTOSYNTHESIS

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RESPIRATION

A.2.– RESPIRATION: All living beings breath, and plants do it too. Plants get oxygen and expel carbon dioxide through stomas in leaves, to transform sugars into energy to grow. Plants breath mainly during the night, so it’s dangerous have plants in the bedroom at night.

16A

16B

Water

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A.3.– TRANSPIRATION: Roots absorb a lot of water from the soil, but only a small amount of this water is used in the phtosynthesis, so plants expel the rest of water by stomatas in the leaves.

USEFUL WORDS: .– autotrophic nutrition .– photosynthesis .– carbon dioxide

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.– xylem sap .– chlorophyll .– glucose /sugars

.– pholem sap .– respiration .- transpiration

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B.– INTERACTION FUNCTION IN PLANTS: Plants don’t have sense organs or nervous system, but plant can react to some stimuli (gravity, light, temperature, humidity…).

They can’t move from the soil, but they can move a bit, for instance their stems and leaves can move to the light, their roots grow down looking for water and nutrients…

Plants react to temperature, or light-time… and adapt their vital cicles to the different seasons through the year.

There are two kinds of reactions: Tropisms and nastic movements. .- Tropism:indicates growth or movement in response to an environmental stimulus. Ìt depends on the direction of the stimulus. .

– Phototropism: movement or growth in response to light. .– Hydrotropism, movement or growth in response to water. 20 19 .– Geotropism, movement or growth in response to gravity.

Geotropism

.– Nastic movements: are non-directional responses independent of the stimulu’s position.

Nastic movement to get food.

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Photropism 22

C.– REPRODUCTION IN PLANTS. Plants can reproduce in two ways: .– Asexual reproduction: by a piece of a branch or root, by spores, bulbs, stolons… .– Sexual reproduction: in flowering plants.

C.1.– SEXUAL REPRODUCTION IN PLANTS WITH FLOWERS: Flowers are the reproductive organs in plants. They have a male part (stamen) and a female part (pistil). .- Stamen produce pollen, that are the male reproductive cells in the plant. .– Pistil produce ovules, that are the female reproductive cells in the plant.

In the reproductive process there are some stages: 1.- POLLINATION. Pollination is the process by which pollen from the anthers of a flower is transferred to the stigma of the same flower or of another flower.

There are different ways of pollination: through animals like birds or insects, 23 through the air or water...

USEFUL WORDS: .– tropism .– nastic movements

.– phototropism .-hydrotropism .– asexual / sexual reproduction

.– geotropism .- pollination

Pollination

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Fertilization

2.- FERTILIZATION. Fertilization occurs when pollen reaches the ovule and starts the beginnings of a new plant.

1.- Pollen falls down on the stigma, and forms a tube (pollen tube).

2.- Through the tube pollen gets the ovary and joins to an egg cell and forms a seed.

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3.- SEED & FRUIT FORMATION. After fertilization, the ovule will transform into a seed, and the ovary will transform into the fruit.

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Seed and fruit formation

GERMINATION OF A BEAN SEED

4.- GERMINATION. Seeds are protected by fruit. If a seed falls down on a soil, and there is enough water and heat, it will germinate and form a new plant.

Germination is the process by which plants emerge from seeds and begin growth. First the seed breaks, the radicle emerges and starts to grow into the soil, later first leaves emerge, producing a new plant.

Leaf Seed coat

Cotyledon Stem

Secondary roots

Primary root

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SEXUAL REPRODUCTION in plants with flowers: 1.– Pollination: pollen from the anthers is transferred to the stigma of the flower.

2.– Fertilization: Pollen forms a pollen tube, and get the ovary to join an egg and form a seed.

3.– Seed and fruit formation: the ovule will transform into a seed, and the ovary into a fruit.

4.– Germination: seed falls down on a soil, with enough water and heat, it will form a new plant.

USEFUL WORDS: .– fertilization .– seed formation .– radicle

.– pollen tube .– germination 28

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C.2.– ASEXUAL REPRODUCTION IN PLANTS:

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Asexual reproduction is the process when a part of only one plant develops into a new young plant.

Types: spores, bulbs, tubers, stolons, vegetative reproduction...

One sorus with spores

1.– Spores: plants without flowers like moss and fern produce spores that germinate and produce new plants.

Fern have sori under their leaves, that produce spores. When spores germinate produce more plants.

Fern leaves

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2.– Bulbs: are short stems with leaves that contain food reserves, and can produce more plants in the following growing season with good conditions of temperature, humidity...

Examples: onions, garlic, tulips…

3.– Tubers: are plant structures that store nutrients, used by plants to survive the winter or dry months. They will produce new plants.

Examples: potatoes, carrots...

Mother plant

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4.– Stolons (or runners): are stems that grow at the soil surface and produce new roots and new plants from the buds.

Examples: strawberries...

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roots

Stolon or runner

5.– Vegetative reproduction: is the process of formation of new plants from a portion of a vegetative part of the plant: root, stem,..

These parts are capable of producing a new entire plant.

36 Examples: most of plants and trees.

USEFUL WORDS: .– spores .– bulbs .– tubers .– stolons / runners .– buds .- vegetative reproduction / propagation