B3 Revison Questions For Chapter

Question 1

What part of an enzymes makes it specific to a particular substrate?

Answer 1

The unique active site.

Question 2

Explain how temperature affects enzyme activity.

Answer 2

A higher temperature increases the rate of reactions at first, but if it gets too hot the enzyme is denatured and the active site changes shape, so the substrate can’t fit any more.

Question 3

State two ways you could measure the rate of enzymes controlled reaction

Answer 3

You could measure how fast a product appears or how fast a substrate disappears

Question 4

Where in a plant cell does photosynthesis take place?

Answer 4

Photosynthesis happens inside subcellular structures called chloroplasts

Question 5

What is the equation for photosynthesis?

Answer 5

Carbon dioxide + water. —light —->glucose +oxygen

Question 6

In the inverse square law, how are light intensity and distance linked?

Answer 6

See p36

Question 7

What effect would a low carbon dioxide concentration have on the rate of photosynthesis?

Answer 7

CO2 is one the substrates needed for photosynthesis, too little carbon dioxide slows down photosynthesis.

Question 8

Define the following terms:
A) diffusion
B) osmosis
C) active transport

Answer 8

A)movement of particles from an area of high concentration to an area of low concentration.

B)movement of water molecules across a partially permeable membrane from a region of high water concentration to a region of lower water concentration.

C)movement of particles across a membrane against a concentration gradient using energy transferred during respiration.

Question 9

Why do multicellular organisms such as plants need specialised exchange surfaces?

Answer 9

Because some cells are deep inside the organism, it is a long way from them to the outside environment, so specialised exchange surfaces are needed to aid transport.

Question 10

If a potato cylinder is placed in a solution with a very high sucrose concentration, what will happen to the mass of the potato cycling ear over time? Explain why.

Answer 10

See.p39

Question 11

What is translocation?

Answer 11

The movement of food substances around a plant.

Question 12

Which type of plant transport vessel is made up of dead cells?

Answer 12

Xylem tubes.

Question 13

How do stomata open and close?

Answer 13

Stomata are surrounded by guard cells, which change shape to control the size of the pore. When the guard cells are turgid (swollen with water) the stomata are open, when the guard cells are flaccid (low on water and limp) the stomata are closed.

Question 14

Give three factors that affect transpiration rate.

Answer 14

An increase in light intensity

An increase in temperature

An increase in air movement

Question 15

Give two resources that plants compete for in ecosystems.

Answer 15

Water, light, space, minerals from soil, seed dispersers and pollinators.

Question 16

Briefly describe how you could use quadrats to investigate the population size of a species.

Answer 16

See p45

Question 17

What is an indicator species and why might you sample one?

Answer 17

See p47

Question 18

How do food webs show interdependence?

Answer 18

Interdependence means that a change in the size of one population will affect the sizes of other populations in the community.

Question 19

What does each bar on a pyramid of biomass represent?

Answer 19

Show mass of living material at that stage of the food chain

Question 20

True or false? Producers always go at the top of a pyramid of biomass.

Answer 20

False. Producers are at the start if the food chain.

Question 21

Why are you unlikely to see a food chain with 10 trophic levels?

Answer 21

Insufficient biomass, because biomass is lost at each trophic level there wouldn’t be enough biomass to support 10 levels.

Question 22

Name a big molecule that’s formed from simple sugars.

Answer 22

Long chain carbohydrates

Question 23

Which two molecules are produced when lipids are broken down?

Answer 23

Fatty acids and glycerol

Question 24

How would you test for the presence of lipids in a sample?

Answer 24

See p52

Question 25

Name two processes that put Carbon back into the air in the Carbon cycle.

Answer 25

Burning fossil fuels
Burning products made from animals and plants
Co2 released from decay
Plant respiration
Animal respiration

Question 26

What is the role of microorganisms in the Carbon cycle?

Answer 26

Decomposers, breakdown waste and dead material.

Fungi and bacteria release CO2 back into air by respiration as they break down material.

Question 27

Give three factors that affect the rate of decomposition.

Answer 27

Water content

Oxygen levels

Temperature