Photosynthesis and Energy in Ecosystems

Question 1

What is the word equation of photosynthesis

Answer 1

Light
Chlorophyll
Carbon Dioxide+Water ————> glucose + oxygen
Enzymes

Question 2

What are the three fates of glucose

Answer 2

-respiration
-starch (storage carbohydrate)
-cellulose (structural carbohydrate)

Question 3

What are the raw materials in photosynthesis

Answer 3

Carbon Dioxide and Water

Question 4

What does photosynthesis do

Answer 4

Traps the light energy from the sun and converts it into chemical energy

Question 5

What indication compound is used to test for the presence of starch

Answer 5

Iodine solution - will change colour from brown/red to blue/black

Question 6

What are the two stage of photosynthesis called ?

Answer 6

Stage 1 - Light reactions (photolysis)
Stage 2 - Carbon Fixation

Question 7

Describe what happens during stage 1 of photosynthesis/light reactions

Answer 7

-Light energy from the sun is trapped by chlorophyll in the chloroplast.
-Light energy is converter into chemical energy which is used to make ATP.
-Water is split into oxygen and hydrogen, oxygen diffuses out of cell but hydrogen is retained for stage 2.

Question 8

Describe what happens in stage 2 of photosynthesis/carbon fixation

Answer 8

A series of enzymes controlled reactions, which use hydrogen and ATP (from stage 1) with CO2 to produce glucose.

Question 9

Why is the carbon fixation stage temperature dependent?

Answer 9

Because carbon fixation is controlled by enzymes - which activity is affected by temperature.

Question 10

What is a limiting factor ?

Answer 10

A limiting factor is one which if in short supply will limit the rate of
photosynthesis, causing it to slow down or come to a halt.

Question 11

What are the three limiting factors that affect the rate of photosynthesis.

Answer 11

-Light intensity, light the source of energy for photosynthesis
-Temperature, Carbon fixation is an enzyme controlled reaction.
-C02 Concentration, C02 provides the plant with a carbon source to make glucose

Question 12

What ways is the majority of energy lost when it moves from one level to another in a food chain ?

Answer 12

-Heat
-Movement
-Indigestible Materials

Question 13

describe the transfer of energy from light arriving at the leaf to the formation of sugar

Answer 13

-Light energy trapped by chlorophyll.
-Light energy is converted into chemical energy which is used to generate ATP (when water is split into hydrogen and oxygen)
-ATP goes from stage 1 to stage 2
-The chemical energy(ATP) is converted into sugar.

Question 14

why is so much energy lost between trophic levels?

Answer 14

An organism only uses a small amount of energy for growth (10%), only energy used in growth is available to the next trophic level.

Question 15

what are level called in a food chain

Answer 15

Trophic levels. (bottom is T.L1)

Question 16

what do pyramids of numbers represent

Answer 16

The number of organisms at each trophic level in a food chain.

Question 17

why does each organisms need to eat more from the trophic level below?

Answer 17

Energy loss usually means that an organisms must eat more prey to gain sufficient energy.

Question 18

what organisms would a pyramid need to represent to have a trophic level of 2 larger than Trophic level 1 (irregular shaped)

Answer 18

a food chain beginning with a tree/bush (mass can be represented to return to true pyramid shape)

Question 19

what are pyramids of energy

Answer 19

Pyramids of energy are a diagram which show the total amount of energy at each trophic level in a food chain, they are always true pyramids.

Question 20

Why do trophic level numbers usually decrease in a pyramid as you go up the pyramid

Answer 20

Numbers usually decrease because energy loss at each stage means less organisms can be supported