Unit 4

Question 1

What is the source of energy for photosynthesis

Answer 1

The sun

Question 2

Name the substance that strengthens cell walls

Answer 2

Cellulose

Question 3

What is meant by an endothermic reaction

Answer 3

Energy is transferred from the environment

Question 4

A lack of magnesium can cause chloroplasts to not make enough chlorophyll. Explain what effect this would have on the rate of photosynthesis

Answer 4

It was decreased, because the chloroplast wouldn’t be able to absorb as much light

Question 5

Suggest two ways that a farmer could improve the conditions for photosynthesis in a greenhouse. Explain these two ways.

Answer 5

Add a heater to increase the temperature which in turn increases photosynthesis rate
Add a paraffin heater to increase CO2 concentration which in turn increases photosynthesis rate

Question 6

Using greenhouses can be costly. Explain why it sometimes beneficial to do this

Answer 6

Because the farm or get a better yield so they will make more profit

Question 7

Give three examples of how our body uses energy transferred by respiration

Answer 7

Keeping warm
Allowing muscles to contract
To build up larger molecules from smaller ones

Question 8

Some metabolic reactions involve using glucose molecules to make other molecules. Name a molecule made from glucose in plants, and a molecule made from glucose in animals

Answer 8

Cellulose

Proteins

Question 9

Describe the components of the lipid molecule

Answer 9

One molecule of glycerol and three fatty acids

Question 10

Briefly describe how protein molecules are formed

Answer 10

Glucose is combined with nitrate ions to make amino acids which are then made into proteins

Question 11

What is excess protein broken down to produce

Answer 11

Urea

Question 12

Why do you use a controlled variable in the Snail and glass beads experiment

Answer 12

To show that it’s the Snail producing carbon dioxide and not something else in the Beaker

Question 13

What’s the word equation for fermentation

Answer 13

Glucose = ethanol + carbon dioxide

Question 14

Compare aerobic respiration and anaerobic respiration in muscle cells

Answer 14

Aerobic respiration in muscle cells uses oxygen, whereas anaerobic respiration doesn’t. Aerobic respiration in muscle cells formed carbon that water, whereas anaerobic respiration forms lactic acid. Aerobic respiration in muscle cells transferred a lot of energy, whereas anaerobic respiration in muscle cells transfer to small amount of energy

Question 15

What could the student have measured to show the effects of exercise

Answer 15

Breath volume
Heart rate
Breaths per minute

Question 16

What physical effects does a long period of exercise have on muscles

Answer 16

It causes them to fatigue and stop contracting efficiently