How do plants grow

Chapter 1(Biology)

PART 2

The process in plants of using light and forming starch is called:PHOTOSYNTHESIS

Energy transfer in photosynthesis

Draw the energy transfer diagram for photosynthesis in your copybook using the following words:1) Chemical energy2) Light energy3) Chlorophyll

ChlorophyllChemical energyLight energy

Energy transfer diagram for photosynthesis

In which organelle is chlorophyll found?

In the chloroplasts.

In which cell is the above organelle found?

Palisade cells

The amount of matter or mass in a living thing.- Biomass can be found out by weighing living

things- The mass of a living thing when it is alive is

called wet biomass.- The accurate measurement is dry biomass

(living thing is killed and dried out and weighed)

Biomass

- Biomass can be used to monitor environmental changes.

- HOW??- The biomass of an animal or plant species

can be found by weighing some individuals and estimating the number in the habitat.

- This can be done from time to time (any change in biomass indicates environmental changes)

- Biomass is also used as a source of renewable energy.

(Plants are grown to be used as fuel)

Minerals- When van Helmont performed the willow tree

experiment he found out that the mass of the soil decreased by 60 g (did not check why).

- Later on scientists studied the soil and discovered that it contains salts (ex. Potassium phosphate and calcium nitrate) needed for plants to grow (MINERAL SALTS)

- These salts are water soluble and are taken by the plant through the roots.

The transport of water through a plant

- Most plant roots have projections called root hairs.

- The tips of the root hairs grow out into the spaces between the soil particles (increase surface area for water absorption).

- The water in the soil is drawn into the plant to replace the water lost through evaporation (Transpiration) from the leaves.

- The plant does not have to use energy to take water in.

- But, the plant needs to use energy to take in the dissolved mineral salts.

- This energy is provided by the root cells when they use oxygen in respiration.

- The roots get oxygen needed for the respiration process from the air spaces between the soil particles.

Tubes for transporting water- There are cells in the plant which form tubes to

transport water.- The cells form columns in the plant and when

they die the walls between them break down to form tubes.

- Each tube is called xylem.

Adaption PurposeLarge surface area To absorb more lightThin Short distance for carbon

dioxide to diffuse into leaf cells

Chlorophyll Absorbs sunlight to transfer energy into chemicals

Network of veins To support the leaf and transport water and carbohydrates

Stomata Allow carbon dioxide to diffuse into the leaf

Features of leaves

Adaption PurposeEpidermis is thin and transparent

To allow more light to reach the palisade cells

Thin cuticle made of wax To protect the leaf without blocking out light

Palisade cell layer at top of leaf

To absorb more light

Spongy layer Air spaces allow carbon dioxide to diffuse through the leaf, and increase the surface area

Palisade cells contain many chloroplasts

To absorb all the available light

Structure of leaves