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SCIENCE 5. UNIT 4. PLANTS. C.E.I.P. SANTA ANA (Madridejos)

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.

USEFUL WORDS:

.– chlorophyll .– autotrophic nutrition .– moss

.– fern .– sori (sorus) .– spores

.– seed plants .– gymnosperms .– angiosperm

1.- CHARACTERISTICS OF PLANTS.

1.– Plants contain chlorophyll (that gives them their

green colour) to produce their own food through the pho-

tosynthesis. So they have autotrophic nutrition.

2.- They can’t move from the soil.

3.- They are multicellular organisms with a nucleus.

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2.– CLASSIFICATION OF PLANTS:There are two groups:

2.1.– Without flowers: like moss and fern (they reproduce them-

selves by spores).

Moss: are very small plants without real roots, stem or

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.

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

spores.

The bonsai is a plant

Fern

Moss

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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 coni-

fers (pines, cypresses…)

b.- Angiosperms: (flowering plants), they produce beautiful flowers

that later will transform into seeds protected by fruits.

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(Gymnosperm) pine tree (Gymnosperm) pine tree

Sori with spores.

(Angiosperm) apple tree

1.- Plants without flowers: moss and fern.

2.– Plants with flowers:

a.– Gymnosperms: naked seeds (pine)

b.– Angiosperms: flower, seeds and fruit (apple)

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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.

3.- PARTS OF A PLANT:

All plants with flowers have the same structure.

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 secon-

dary 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,

and they make food for the plant in the process of photo-

synthesis.. It has two parts:

.- The petiole: links the leaf to the stem.

.– 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 sea-

sons, and deciduous plants that lose their leaves during

Autumn.

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 or-

gans.

.- 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).

stomata

vein midrib

petiole

blade

.– roots .– root hairs .- stem .– trunk

.– leaves .– petiole .– blade .– stomata

.– flowers .– petals /corolla .– sepals/calyx .– stamen

.– anther .– filament .– pistil .– stigma

.– style .– ovary .– ovules .– seeds

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

USEFUL WORDS:

.– autotrophic nutrition .– xylem sap .– pholem sap

.– photosynthesis .– chlorophyll .– respiration

.– carbon dioxide .– glucose /sugars .- transpiration

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.

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.

A.2.– RESPIRATION:

All living beings breath, and plants do it too. Plants get oxy-

gen 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.

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.

Water

RESPIRATION

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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.

PHOTOSYNTHESIS

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16B

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USEFUL WORDS:

.– tropism .– phototropism .-hydrotropism .– geotropism

.– nastic movements .– asexual / sexual reproduction .- pollination

B.– INTERACTION FUNCTION IN PLANTS:

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 environmen-

tal 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.

.– Geotropism, movement or growth in response to gravity.

.– Nastic movements: are non-directional responses independent of the

stimulu’s position.

Plants don’t have sense organs or nervous system, but plant can react to

some stimuli (gravity, light, temperature, humidity…).

Photropism

Geotropism

Nastic movement

to get food.

C.– REPRODUCTION IN 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,

through the air or water...

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Plants can reproduce in two ways:

.– Asexual reproduction: by a piece of a branch or root, by spo-

res, bulbs, stolons…

.– Sexual reproduction: in flowering plants.

Pollination

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USEFUL WORDS:

.– fertilization .– pollen tube

.– seed formation .– germination

.– radicle

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.

2.- FERTILIZATION.

Fertilization occurs when pollen reaches the ovule and starts the be-

ginnings 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 trans-

form into a seed, and the ovary will

transform into the fruit.

Fertilization

Seed and fruit formation 26

4.- GERMINATION.

Seeds are protected by fruit. If a

seed falls down on a soil, and there is

enough water and heat, it will germi-

nate 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. Primary root

Cotyledon

Seed coat

Leaf

Stem

Secondary roots

GERMINATION OF A BEAN SEED

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USEFUL WORDS:

.– spores .– bulbs .– tubers .– stolons / runners

.– buds .- vegetative reproduction / propagation

C.2.– ASEXUAL REPRODUCTION IN PLANTS:

1.– Spores: plants without flowers like moss and fern pro-

duce spores that germinate and produce new plants.

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

spores germinate produce more plants.

One sorus with spores

Asexual reproduction is the process when a part of

only one plant develops into a new young plant.

Types: spores, bulbs, tubers, stolons, vegetative re-

production...

Fern leaves

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...

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.

Examples: most of plants and trees.

4.– Stolons (or runners): are stems that grow at the soil surfa-

ce and produce new roots and new plants from the buds.

Examples: strawberries...

Mother plant

New plant

roots Stolon or runner

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