Plants at work

J E F Frost Plants at work 1

Plants are producers

Plants get their energy from light Plants make food by photosynthesis Light energy is trapped by chlorophyll Most of the food is stored as starch J E F Frost Plants at work 2

Photosynthesis Word equation

sunlight Carbon dioxide + water sugar + oxygen chlorophyll Plants make new biomass during photosynthesis J E F Frost Plants at work 3

Leaves

Leaves are green because they contain chlorophyll Leaves have a large surface area to absorb as much light as possible J E F Frost Plants at work 4

Testing for starch

Iodine changes from brown to blue black where there is starch

Method

Soften the leaf with boiling water Remove the green colour with ethanol Add drops of iodine Look for the colour change!

J E F Frost Plants at work 5

Variegated leaves

Some leaves are not green all over Some have white and green stripes or patches Only the green parts will contain starch

Why?

J E F Frost Plants at work 6

Respiration in plants

All living things carry out respiration Leaves are thin so that gases can get in and out easily Gases get into and out of leaves through little holes called stomata J E F Frost Plants at work 7

Section through a leaf

Waxy layer Palisade cells Spongy cells Air space Guard cell Lower surface J E F Frost Plants at work Stomata 8

Plant growth

• Plants need carbon dioxide from the air • Plants need water • Plants need light • Plants need nutrients from the soil including nitrogen, phosphorus and potassium • If the soil does not contain enough nutrients then we add fertilisers J E F Frost Plants at work 9

Fertilisers

Nitrogen is needed for general growth Phosphorus is needed for healthy roots Potassium is needed for healthy leaves J E F Frost Plants at work 10

Plant plumbing

Water and minerals enter the plant through the roots Then they go up through little tubes called xylem in the plant stem Food is transported through tiny tubes in the stem called phloem J E F Frost Plants at work 11

Roots

Roots keep the plant anchored in the soil Roots are covered in lots of tiny hairs Root hairs take up water from the soil All the root hairs together have a large surface area J E F Frost Plants at work 12

Flowers

Flowers are a plant’s reproductive system Flowers have male and female reproductive organs Male part (stamen): anther and filament Female part (carpel): stigma, style, ovary J E F Frost Plants at work 13

Pollination

Pollination is the transfer of pollen (male) to the stigma (female) Pollen grains can be carried by insects Pollen grains can be carried by the wind When the ovule is fertilised it turns into a seed J E F Frost Plants at work 14

stigma

Making seeds

Pollen grain style ovary J E F Frost ovule ovule nucleus Plants at work 15

plant seed root stem leaf root hair starch

Key words

chlorophyll photosynthesis carbon dioxide oxygen phosphorus nitrogen potassium pollen anther filament stigma style ovule xylem phloem J E F Frost Plants at work 16