Producers

Examples of plants

Why are plants producers?

• Because only plants can combine light energy from the sun with raw materials from the environment e.g. water, air to make food molecules.

• Food has chemical potential energy and herbivores...etc are able to break food down and take in energy

Plants are Food factories

• Plants undergo photosynthesis, (making food using light).

Photo = light; synthesis = making. • Note: 1.Oxygen is used for respiration2.Carbon dioxide is used for

photosynthesis3.It only occurs during the day when light is

available.

Plants

• All organisms need food to survive, food provides e_______.

• Plants are multicellular organisms. They contain a green substance called Chlorophyll and can make food called Carbohydrates – sugar and starch.

Parts of plants

• Roots; root hairs

• Stem; Xylem and phloem

• Petiole• Leaf; Stomata, cuticle

• Seed• Flowers

Picture of a plant

How does photosynthesis work?

1. The process occurs inside the leaves.2. Water, Carbon dioxide gas and sunlight

rays are needed for photosynthesis to occur.

3. Glucose sugar, oxygen gas are the products.

Photosynthesis equation: photosynthesis

CO2 + H2O + Sunlight Glucose sugar + O2

The rate of photosynthesis

• Depends on the abundance of reactants. For example: light intensity , CO2 and water concentration,.

• However all reactions are faster in warmer rather than colder conditions.

• We can scientifically measure the rate by measuring the growth in size of plants or by the production of oxygen.

Quiz1. Why are plants food factories?(1m)2. Name all substances needed for plants to

produce food and all the products? (6m)3. At day time, what gas(es) do plants produce?

Through what process(es)? (2m)4. At night time what gas(es) do plants produce?

Through what process(es)? (2m)5. What is the green substances in the leaves ?

(1m)6. What does Synthesis mean? (1m)7. What tube does plants use to transport food?

(1m)

Cross section of a leaf

Stomata

• pores allow gas exchange and control water loss.

Structure and Functions of leaves• Cuticles: A waxy layer which helps to reduce water loss.

• Upper epidermis: outer cell layer• Spongy cells: contain fewer chloroplasts because light

is weaker, cells are well spaced out allowing gases to circulate.

• Guard cells: control the size of the stomata pores which let gases in or out.

• Lower epidermis: bottom cell layer.• Veins: have xylem tubes ( water from roots to the whole

plant) and phloem tubes ( food from leaves to the whole plant)

• Palisade layer cells: have lots of chlorophyll for photosynthesis.

Adaptations of plants• Plants need the following things to survive:1. minerals2. water 3. sunlight4. warmth5. air

• They develop special features to survive in different environments:

3 types of adaptations:1.Structural adaptation: visible features; e.g. thin needle like

leaves.

2.Functional(physiological)adaptation: Life processes, e.g. photosynthesis,

respiration.

3. Behavioural adaptation: Behaviours that plants exhibits, e.g.

plants growing towards light.

Structural adaptations of leaves:

External adaptation1.Wide blade: captures maximum sunlight.2.Thin leaf: allows maximum light penetration3.Vein network:supports leaf, transport water and sugar and minerals4.Green colour: Chlorophyll to trap sunlight.5.Pores in leaf: allow gas movement through the leaf6.Waxy surface: prevent excessive water loss7.Strong petiole: holds leaf up to sunlight

Internal adaptations:1.Epidermis layer cells: Protect the leaf and reduce water loss by

making the waxy surface.2.Palisade layer cells: Contain lots of chlorophyll3.Spongy layer cells: Well spaced to maximize light and gas

absorption4.Veins: Bring water from the roots and phloem tubes,

carry sugars around.5.Guard cells: Control the size of the stomata pores.

Transpiration• Loss of water from the leaves of a plant by

evaporation.• Water first enters plants through the roots

(root hairs). Water is absorbed into the root by osmosis.

• Water travels up the plant to the leaves through (small microscopic/ capillary tubes) by capillary action.

• Eventually water reaches the stomata then escape through evaporation.

• Xylem experience a loss in pressure, so water is sucked up the xylem through suction pressure.

Transpiration increases when:

1. The leaf stomata are open

2. The air is dry3. It is warm4. It is windy5. The leaves have

a large surface area

Osmosis• Osmosis is the process by which water is absorbed into

roots.• The root hair’s surface is a semi permeable membrane. • Water always moves from a higher concentration to a

lower concentration.• The larger the concentration difference, the faster the

movement (diffusion) of water.• E.g. A dry towel absorbs water faster then a wet towel.• Water is diffused into the root from the soil if the water

concentration is higher/lower in the soil.

Absorption of water by plants

• A plant’s root system maximizes water uptake in 2 ways:

1. Taproot: grows downwards to access water deep in the ground.

2. Lateral roots: sideway roots which access water closer to the surface.

Plant classification

Angiosperm

Flower bearing plants

Gymnosperm• Cone bearing plants

Angiosperms, flowering plants, are divided into two groups:

• monocots

• Dicots

•dicots.

Plant reproduction• Plants can reproduce asexually or

sexually.• Asexual reproduction • as runners (strawberries) or side

branches (busy lizzy). • as potatoes, storage organs develop

underground which grow into new plants. This is called vegetative propagation and examples include tubers, bulbs and rhizomes.

• cuttings or grafts, which can grow into a new plant.

Sexual reproduction

• Plants can also reproduce by sexual reproduction. The offspring have the genes from two parents - their genes are different, so the offspring will not be identical. There is variety in the species.

Flower parts

• Petals- attracts insects• Stamen- male sex organ• Anther – produce pollen

grains• Filaments- rises the

anther• Carpel – female sex

organ• Sepal – protects the

flower when it is a bud

Flower