Biology - Chapter 6 - Plant structures and their functions

Where does photosynthesis take place?

In the leaves within the sub-cellular structures chloroplasts which contain chlorophyll which absorb light

What is the word equation for photosynthesis?

Carbon dioxide + water → glucose + oxygen

What is the symbol equation for photosynthesis?

6Co2 + 6H2O → C6H12O6 + 6O2

Is photosynthesis endothermic or exothermic?

Endothermic

How does photosynthesis happen?

Carbon dioxide diffuses into the leaves through the stomata, water is taken up from the soil by roots and is transported to leaves via xylem

What is cellular respiration for?

To release energy

What is cellulose for?

To strengthen cell walls

What is starch?

A long term, compact, insoluble store of glucose

What does starch do when needed?

Breaks down

What does the growth rate of plants depend on?

How fast they can photosynthesize

What do amino acids break down into?

Glucose and nitrate ions

What do glucose and nitrate ions break down into?

Proteins

What are the four factors that affect photosynthesis?

Light intensity, temperature, carbon dioxide and chlorophyll concentration

Why does temperature affect photosynthesis?

Enzymes work quickly with a greater temp causing the molecules to move faster

What are the three reasons why chlorophyll levels can vary?

Due to disease, lack of nutrients and environmental stress

What does plateaued mean?

Another factor is limiting the rate of the reaction

How can artificial conditions be created by farmers for photosynthesis?

Greenhouses, artificial lights, paraffin heaters, fertilisers, pesticides

What are the advantages and disadvantages for farmers creating artificial conditions for photosynthesis?

Increased profit from a greater yield but expensive to setup and manage

Draw and label the plant cell organisation

Where is the stoma located?

In-between two guard cells

How are guard cells adapted for their function?

They are turgid, making the gap larger so that more CO2 is able to diffuse through

What do guard cells do when a plant is short of water?

They become flaccid which closes the stoma to conserve water vapour

What happens to guard cells at night?

They close

Are stoma located on the shady or sunny side?

Shaded side

Why are stoma located on the shady side?

So that there is less evaporation

What is translocation?

The transporting of sugars via phloem cells

Can phloem cells transport one way or both directions?

Both directions

What do phloem cells have which allow cell sap to pass through?

Pores

What are xylem tubes made up of?

Dead xylem cellsW

What are xylem tubes strengthened by?

Lignin

What do xylem tubes transport?

Water and mineral ions

What is transpiration?

Evaporation of water from the leaves

What are the four factors affecting transpiration?

Temperature, light intensity, air flow, humidity (more humid decreases rate)

What do plant hormones do when they sense light?

Grow towards the light to maximise photosynthesis

What do plant hormones do when they sense gravity?

Grow roots downwards

What do plant hormones do when they sense touch?

Climb around objects

Do plant hormones act locally or internationally?

Locally

What do auxins control?

The growth at roots and shoots

What do auxins in shoots do?

Stimulate growth

What do auxins in roots do?

Inhibit growth

What is phototropism?

respond to light

What is gravitropism?

Respond to gravity

Where do auxins always accumulate?

On the lower, shaded sides

In terms of phototropism and gravitropism, what are shoots?

Positively phototropic, negatively geotropic

In terms of phototropism and gravitropism, what are roots?

Negatively phototropic, positively geotropic

What does gibberellin do?

Controls dormancy, flowering, grow larger fruit

What does ethene do?

Stimulate the ripening of fruit

How is ethene useful comercially?

Controls ripening process so that it can be transported and exposed to ethene when ready to be sold