2Y: Respiration and Photosynthesis

Question 1

What is Energy?

Answer 1

Energy is the ability to do work.

Question 2

When is Work done?

Answer 2

Work is is done when a body is moving.

Question 3

What is Respiration?

Answer 3

Respiration is the release of energy from food.

Question 4

Is Respiration a chemical process or a biological process?

Answer 4

Respiration takes place in living cells. Therefore, as well as being a chemical process it is also a biological process.

Because respiration is both a chemical and a biological process, it may be called a biochemical process.

Question 5

Where does Respiration take pace?

Answer 5

Respiration takes place in cells.

All living things respire – either aerobically or anaerobically.

Question 6

What is Aerobic Respiration?

Answer 6

Aerobic Respiration is the release of energy from food when oxygen is in the reaction.

Question 7

What is the word equation for Aerobic Respiration? (written in words)

Answer 7

glucose + oxygen =>
energy + carbon dioxide + water

Question 8

What is Anaerobic Respiration?

Answer 8

Anaerobic Respiration is the release of energy from food when oxygen is not in the reaction.

Question 9

What is the word equation for Anaerobic Respiration? (written in words)

Answer 9

1. glucose => energy + ethanol + carbon dioxide….or
2. glucose => energy + lactic acid
3. Occurs in yeast – to form alcohol in the process called fermentation
4. Occurs in animals (including humans) – to form lactic acid in muscles. This is what causes cramp during exercise. So, if you exercise for a long time and are not getting enough oxygen to your muscles for aerobic respiration, anaerobic respiration takes place, lactic acid is produced and you get cramp.

Question 10

What 3 Factors affect respiration?

Answer 10

The following 3 factors affect respiration:

1. • Glucose availability
2. • Oxygen availability
3. • Temperature

Question 11

Why does Glucose and Oxygen affect respiration?

Answer 11

Glucose and oxygen are involved in the reaction that is respiration.

Glucose is the fuel in the reaction. If there is not sufficient fuel, the reaction will be slow or stop.

Oxygen is needed to react with the glucose during the process of respiration. If there is not sufficient oxygen, the reaction will be anaerobic and very little energy will be released.

Question 12

Why does temperature affect respiration?

Answer 12

• All biochemical processes are controlled by enzymes.
• Enzymes are proteins that work at a particular temperature, for example enzymes in the human body require a temperature of 37 °C to work best.
• Enzymes cannot function when frozen.
• Enzymes are destroyed at high temperatures.

Question 13

What is Photosynthesis?

Answer 13

Photosynthesis is the way plants make their own food using light.

Photo = light
Synthesis = produce/make

Question 14

What is the word equation for photosynthesis?

Answer 14

carbon dioxide + water =>

chlorophyll - sunlight

=> glucose + oxygen

Question 15

How do plants photosynthesise?

Answer 15

For photosynthesis to take place:

1. Plants take in carbon dioxide from the air through tiny pores on their leaves called stomata (singular stoma).
2. Plants take in water from the soil through their roots.
3. Sunlight is absorbed by the chloroplasts in the cells of the leaves of the plant.
4. The green pigment chlorophyll, in the chloroplasts, allows the carbon dioxide and water to combine to form glucose.
5. The energy for this reaction comes from sunlight.
6. Oxygen is released and given off as a waste product.

Question 16

Is Photosynthesis a chemical process or a biological process?

Answer 16

1. Photosynthesis as a chemical process because there are new substances formed and;
2. It is a biological process because it happens in living cells.

Question 17

What 3 Factors affect Photosynthesis?

Answer 17

The factors affecting photosynthesis are:

1. Carbon dioxide
2. Temperature
3. Light

Carbon dioxide:

• If carbon dioxide levels fall or rise, the rate of photosynthesis will also fall oe rise. This is because there will be less or more of the gas to take part in the photosynthesis reactions.

Temperature

• As we have seen already, all biological processes are controlled by proteins called enzymes. Enzymes need a particular temperature to work efficiently. If the temperature is too low, the enzymes slow down and so also does the rate of the reaction. On the other hand, if temperature goes too high, the enzymes may be destroyed and so the reaction will stop.

Light

• Light provides the energy for the reactions to occur in photosynthesis. If the light intensity (strength of the light) is low, the rate of photosynthesis will be low due to the lack of energy. As light intensity increases, so too does the rate at which photosynthesis occurs.

Question 18

How does knowledge of photosynthesis affect plant yields?

Answer 18

Growers use the knowledge that

• Carbon dioxide
• Temperature
• Light

affect the rate of photosynthesis.

1. Greenhouses raise the temperature so that plants will photosynthesise more efficiently and produce better crops.
2. Growers also add carbon dioxide to greenhouses to increase the yield of their crops.
3. Light adjustments can also be made to increase the rate of photosynthesis, for example ‘lighting rigs’ are brought into Croke Park to improve the grass growth in the shaded parts of the stadium.
4. Artificial light and warmer temperatures due to heaters means that certain foods that were once seasonal can now be available all year-round.

Question 19

Describe the three very important functions photosynthesis carries out for the continued existence of life on Earth?

Answer 19

1. Photosynthesis results in plants giving off oxygen, which is essential for many living organisms.
2. Photosynthesis removes carbon dioxide from the air and prevents it from reaching a poisonous level.
3. Photosynthesis provides food for most living organisms on Earth.

Question 20

What is the Carbon Cycle?

Answer 20

The constant recycling of carbon atoms is known as the carbon
cycle.
Photosynthesis is how carbon in the form of carbon dioxide gas gets
fixed(caught up) in compounds such as food and fuels. Photosynthesis is vital for keeping the carbon cycle going and therefore keeping life on
Earth, as we know it, going too.