B4

Question 1

What is photosynthesis?

Answer 1

An endothermic reaction (requires input energy) in which energy is transferred from the environment to the chloroplasts by light

Question 2

State the word equation for photosynthesis

Answer 2

……………………………………..Light
Carbon dioxide + Water ——–> Glucose+Oxygen
Chlorophyll

Question 3

What is the symbol equation for photosynthesis?

Answer 3

6CO2 + 6H2O —————–> C6H12O6 + 6O2

Question 4

What is the effects of temperature on photosynthesis?

Answer 4

• At low temperatures, the rate of photosynthesis is limited by the number of collisions between enzymes and substrate
• As temperature increases the number of collisions increases, therefore the rate of photosynthesis increases

Question 5

What is the effects of light intensity on photosynthesis?

Answer 5

The rate of photosynthesis is directly proportional to light intensity and inversely proportional to the distance from a light source

Question 6

What can be described because of the inverse square law?

Answer 6

The intensity of light at different distances from a light source

Question 7

What is the effects of carbon dioxide concentration on photosynthesis?

Answer 7

If the concentration of carbon dioxide is increased, the rate of photosynthesis will therefore increase.

Question 8

What is the effects of the amount of chlorophyll concentration on photosynthesis?

Answer 8

• The amount of chlorophyll also affects the rate of photosynthesis: plants in lighting conditions unfavourable for photosynthesis synthesise more chlorophyll, to absorb the light required.
• The effects of some plant diseases affect the amount of chlorophyll, and therefore the ability of a plant to photosynthesise.

Question 9

What are the limiting factors in photosynthesis (stops making photosynthesis happen any faster) ?

Answer 9

Intensity of light, CO2 concentration and temperature

Question 10

Note:

Answer 10

AQA says that students should be able to:

• Measure and calculate rates of photosynthesis
• Extract and interpret graphs of photosynthesis rate involving one limiting factor
• Plot and draw appropriate graphs selecting appropriate scale for axes
• Translate information between graphical and numeric form

(Check goodnotes Biology B8 Folder which has the rate of photosynthesis with explanations)

Question 11

Note:

Answer 11

AQA says that students should be able to explain graphs of photosynthesis rate involving two or three factors and decide which is the limiting factor

Question 12

Why are limiting factors important in the economics of farmers?

Answer 12

As they need to enhance the conditions in greenhouses to gain the maximum rate of photosynthesis while still maintaining profit

Question 13

What do farmers do to enhance the conditions in greenhouses?

Answer 13

• Plants in greenhouses are often sprayed with water to keep the humidity high
• Growers must find a balance as high humidity will promote the growth of pathogenic fungi
• Irrigation systems are also used outdoors
• Ventilation is also used

Question 14

Practical 5

Answer 14

AAA

Question 15

What is the glucose produced in photosynthesis used for?

Answer 15

• Used for respiration
• Converted into insoluble starch for storage
• Used to produce fat or oil for storage
• Used to produce cellulose, which strengthens the cell wall
• Used to produce amino acids for protein synthesis

Question 16

To produce proteins what do plants use?

Answer 16

Nitrate ions that are absorbed from the soil

Question 17

What is cellular respiration?

Answer 17

• An exothermic reaction which is continuously occuring in living cells
• The energy transferred supplies all the energy needed for living processes

Question 18

What can respiration take place in?

Answer 18

Respiration in cells can take place aerobically(using oxygen) or anaerobically(without oxygen), to transfer energy

Question 19

What is aerobic respiration in regard to the need for oxygen,the differing products and the relative amounts of energy transferred?

Answer 19

• Aerobic respiration breaks down glucose and combines the broken down products with oxygen, making water and carbon dioxide
• The carbon dioxide is a waste product of aerobic respiration because cells do not need it

Question 20

What is anaerobic respiration in regard to the need for oxygen,the differing products and the relative amounts of energy transferred?

Answer 20

• Anaerobic respiration happens in muscles during hard exercise
• Glucose is not completely broken down, so less energy is released than during aerobic respiration
• There is a build-up of lactic acid in the muscles during vigorous exercise
• The lactic acid needs to be oxidised to carbon dioxide and water later.

Question 21

What do organisms need energy for?

Answer 21

• Chemical reactions to build larger molecules
• Movement
• Keeping warm

Question 22

How is aerobic respiration represented by a word equation?

Answer 22

Glucose + Oxygen ———–> Carbon dioxide + Water

Question 23

How is aerobic respiration represented by the symbol equation?

Answer 23

C6H12O6 + 6O2 → 6CO2 + 6H2O

Question 24

How is anaerobic respiration in muscles represented by the equation?

Answer 24

Glucose —> Lactic acid

Question 25

Why is less energy transferred in anaerobic respiration than aerobic respiration?

Answer 25

As the oxidation of glucose is incomplete so much less energy is transferred

Question 26

How is anaerobic respiration in plant and yeast cells represented in the word equation?

Answer 26

Glucose -----> Ethanol + Carbon dioxide

Question 27

How is anaerobic respiration in yeast cells important and what is it called?

Answer 27

Anaerobic respiration in yeast cells is called fermentation and has economic importance in the manufacture of bread and alcoholic drinks

Question 28

What happens to the human body during exercise?

Answer 28

During exercise the human body reacts to the increased demand for energy

Question 29

What increases in the human body during exercise?

Answer 29

The heart rate, breathing rate and breath volume increase during exercise to supply the muscles with more oxygenated blood

Question 30

What happens if insufficient oxygen is supplied anaerobic respiration takes place in muscles?

Answer 30

- If insufficient oxygen is supplied anaerobic respiration takes place in muscles - The incomplete oxidation of glucose causes a build up of lactic acid and creates an oxygen debt - During long periods of vigorous activity muscles become fatigued and stop contracting efficiently.

Question 31

When blood is flowing though the muscles, where does it transport the lactic acid?

Answer 31

- Blood flowing through the muscles transports the lactic acid to the liver where it is converted back into glucose - Oxygen debt is the amount of extra oxygen the body needs after exercise to react with the accumulated lactic acid and remove it from the cells

Question 32

What is the importance of sugars in the synthesis and breakdown of carbohydrates?

Answer 32

- Simple sugars such as monosaccharides are linked together through glycosidic linkage to generate carbohydrate strictures in a process known as carbohydrate synthesis - Similarly, the carbohydrates (present in food) undergo breakdown to generate the sugar or monosaccharide units that are easily absorbed into the body - Thus, the importance of sugar is that it serves as the main substrate for the synthesis of carbohydrate molecules and after the breakdown of carbohydrates, it serves as the main product generated

Question 33

What is the importance of amino acids in the synthesis and breakdown of carbohydrates, proteins and lipids?

Answer 33

- The amino acid is the precursor molecule that when linked together through the peptide bonds forms a protein molecule - The amino acids thus serve as the monomer units for the synthesis of the proteins - The breakdown of proteins results in the loss of the peptide linkage and it results in the generation of amino acid monomers that are easily absorbed by the body or for further degradation

Question 34

What is the importance of fatty acids in the synthesis and breakdown of lipids?

Answer 34

- The fatty acids and the glycerol are the backbones of the lipid molecules - A general mechanism for the synthesis of the lipid molecule is the reaction between the hydroxyl group on the glycerol and the carboxyl group on the fatty acids - The fatty acids and the glycerol thus are the main substrates for the synthesis of lipid molecules - The fatty acids and the glycerol are also the products generated after the breakdown of the lipid in the body - These fatty acids and glycerol molecules are easier for the body to process

Question 35

What is the importance of glycerol in the breakdown of lipids?

Answer 35

- Glycerol serves as the backbone of lipid molecules. - It plays a central role in the formation of acylglycerols (simple lipids) and phospholipids (complex lipids)

Question 36

What is metabolism?

Answer 36

The sum of all the reactions in a cell or the body

Question 37

What is the energy transferred by respiration used for?

Answer 37

It is used by the organism for the continual enzyme controlled processes of metabolism that synthesise new molecules

Question 38

What does metabolism include?

Answer 38

* Conversion of glucose to starch, glycogen and cellulose * The formation of lipid molecules from a molecule of glycerol and three molecules of fatty acids * The use of glucose and nitrate ions to form amino acids which in turn are used to synthesise proteins * Respiration * Breakdown of excess proteins to form urea for excretion