Unit 3.3 Photosynthesis & 3.4 Energy

Question 1

Food chain

Answer 1

Shows feeding relationships within a food web. Arrows represent energy flow.

Question 2

Food web

Answer 2

Shows feeding relationships within a community.

Made of many inter-linked food chains.

Question 3

Photosynthesis

Answer 3

Plants use captured light energy to build food molecules such as glucose.

Question 4

Chlorophyll

Answer 4

Green pigment found in chloroplasts inside leaf cells which is used to capture light energy.

Question 5

Chloroplast

Answer 5

Organelle (compartment) inside leaf cells which contains chlorophyll.

Question 6

Light reactions

Answer 6

1st stage of photosynthesis in chloroplast membranes.

Light energy is captured by chlorophyll and is used to split water (photolysis), releasing hydrogen and oxygen (which diffuses from the cell).

It is also used to make ATP.

Question 7

Carbon fixation

Answer 7

2nd stage of photosynthesis in chloroplasts.

Carbon dioxide diffuses in and combines with hydrogen to make sugar (glucose), using energy from ATP.

It is enzyme controlled.

Question 8

Iodine

Answer 8

Used to test for starch.

Turns from orange to blue/black

Question 9

Starch

Answer 9

Carbohydrate made from many glucose molecules joined together.

Used for energy storage.

Question 10

Cellulose

Answer 10

Structural carbohydrate made from many glucose molecules joined together.

Used to build cell walls.

Question 11

Limiting factors

Answer 11

Factors that limit or reduce the rate of photosynthesis eg. light intensity, temperature and carbon dioxide concentration.

Question 12

ATP

Answer 12

Energy storage and transfer molecule.

Energy is used to add a phosphate to ADP creating a high energy bond which can be broken quickly when energy is required.

Question 13

Pyramid of numbers

Answer 13

Shows the number of organisms present at each level of a food chain.

Not always pyramid shaped if you count one tree, or if you include parasites which produce a top-heavy pyramid.

Question 14

Pyramid of energy

Answer 14

Shows the quantity of energy contained in the tissues of all organisms at each level of the food chain.

Always pyramid shaped, due to loss of energy between levels.

Question 15

10% energy transfer

Answer 15

The quantity of energy transferred between levels in a food chain and used to produce tissue.

90% is lost as heat, through movement, respiration and egestion of undigested materials.