B8

Question 1

Is photosynthesis an endothermic or exothermic reaction?

Answer 1

Photosynthesis is an endothermic reaction as it requires an input of energy

Question 2

Fill in the gaps:
During Photosynthesis _____ is transferred from the __________ to the _________ by light. It is used to convert carbon dioxide and _____ into ______(glucose). _____ is also formed and released as a _________.

Answer 2

1) energy
2) environment
3) chloroplast
4) water
5) sugar
6) oxygen
7) by-product

Question 3

Photosynthesis can be summarised as followed (including balanced equation)

Answer 3

Light energy
Carbon Dioxide + water ——->. glucose + oxygen
Chloroplasts

Balanced equation

                                                 Chloroplasts Balanced equation: 6CO₂ + H₂O ------> C₆H₁₂O₆+ 6O₂
                                                Light energy

Question 4

What are ways leaves have adapted to allow the maximum amount of photosynthesis

Answer 4

Broard leaves for a bigger surface area for light to fall on
Thin leaves so diffusion distances for the gases are short
They contain chlorophyll in the chloroplasts to absorb light
They have veins which bring water in the xylem of the cells of the leaves and remove the products of photosynthesis in the phloem
They have air spaces that allow carbon dioxide to get the cells, and oxygen to leave by diffusion.
They have guard cells that open and close the stomata to regulate gas exchange.
These adaptations means that the plant can photosynthesise as much as possible whenever there is light available.

Question 5

During photosynthesis where does the carbon dioxide and water come from

Answer 5

The carbon comes from the atmosphere where CO2 diffuses in from the air via the stomata
The water comes from the soil and is transported in the xylem (the transpiration system)

Question 6

What is oxygen used for

Answer 6

Respiration for the plant

Question 7

What is the glucose used for

Answer 7

To build cellulose for strengthening their cell walls

To build starch as glucose is soluble in water (unlike starch) which could affect the way water moves into and out of the cells (by osmosis).

To make amino acids which build up into proteins to be used in the plant cells in many ways, including as enzymes. They make amino acids by combining sugars with nitrate ions mineral ions from the soil

To make lipids to be used as an energy store. Sometimes used to make cell walls stronger

Question 8

Where is starch kept

Answer 8

It is kept in special storage areas of a plant. Many plants produce tubers and bulbs that are full of stored starch to help them survive through winter.

Question 9

In words what is photosynthesis

Answer 9

Photosynthesis is when chloroplasts harness light energy to convert carbon dioxide and water into glucose.

Question 10

Light intensity relationship mathematically

Answer 10

The light intensity is inversely proportional to d(squared)

L(light) x 1/d(squared)