B4 - Bioenergetics

Question 1

What is the word equation for photosynthesis?

Answer 1

Carbon dioxide + water → oxygen + glucose

Question 2

What is the balanced symbol equation for photosynthesis?

Answer 2

6CO2 + 6H2O → C6H12O6 + 6O2

Question 3

What are the reactants of photosynthesis?
What are the products?

Answer 3

Reactants:
Water and carbon dioxide

Products:
Oxygen and glucose

Question 4

Where in plants does photosynthesis take place? Why?

Answer 4

In all the green parts of the plant.

Because chlorophyll, which is used for light absorption, in the chloroplasts produce a green colour.

Question 5

Why are leaves adapted to be broad and flat?

Answer 5

To give a large surface area which help to absorb lots of sunlight.

Question 6

Why are leaves adapted to have lots of chloroplasts?

Answer 6

Chloroplasts have chlorophyll to absorb lots of sunlight.

Question 7

How do plants use the glucose created from photosynthesis?

Answer 7

C - glucose is converted into cellulose which strengthens cell walls
R - glucose is broken down through respiration to release energy
O - glucose is turned into lipids (oils or fats) and store in seeds
P - glucose is combined with nitrate ions to create amino acids which then are made into protein
S- glucose is turned into starch and stored for when there is no photosynthesis happening

Question 8

What is a limiting factor?

Answer 8

Any environmental variable that may limit the rate of photosynthesis if it is in short supply.

Question 9

How is the rate of photosynthesis affected by light intensity?

Answer 9

Light intensity is needed for energy in photosynthesis.

As light intensity increases energy increases. This means the rate of photosynthesis increases until light intensity is no longer a limiting factor.

Question 10

How is the rate of photosynthesis affected by concentration of carbon dioxide?

Answer 10

CO2 is a raw material needed for photosynthesis.

As the concentration of CO2 increases the rate of photosynthesis increases until the concentration of CO2 is no longer a limiting factor.

Question 11

How is the rate of photosynthesis affected by temperature?

Answer 11

The right temperature is a needed for the enzymes to work in photosynthesis.

As temperature increases the rate of photosynthesis increases until the temperature is too high.
(This will denature the enzymes needed for photosynthesis)

Question 12

Pondweed practical

How does oxygen production show the rate of photosynthesis?

Answer 12

There are bubbles in the water
This is oxygen gas
Which is released when photosynthesis occurs

Question 13

In the limiting factors practical, what is the independent variable?

Answer 13

Light intensity - the distance between the lamp and pondweed

Question 14

In the limiting factors practical, what is the dependant variable?

Answer 14

Rate of photosynthesis- the number of bubbles produced

Question 15

What is the inverse square law?

Answer 15

Light intensity decreases in proportion to the square of the distance

Light intensity ∝ 1/distance^2

Question 16

How are greenhouses used to create the ideal conditions for photosynthesis?

Answer 16

So that temp is not a limiting factor:
• Greenhouses help trap suns heat
• Use heater in winter
• Use shades & ventilation in summer

So that light is not a limiting factor:
• Artificial light used after sunsets
• More time for photosynthesis

So that CO2 is not a limiting factor:
• Paraffin heater

For healthy growth:
• Enclosed greenhouse keeps away pets and diseases
• Fertilisers to provide all minerals

Question 17

Explain how photosynthesis is an endothermic reaction?

Answer 17

Energy is transferred from the environment in the process

Question 18

What is respiration?

Answer 18

The process of transferring energy from glucose, which goes on in every cell.

Question 19

Explain how respiration is an exothermic reaction?

Answer 19

Energy is transferred to the environment

Question 20

How and why is glucose used during respiration?

Answer 20

The glucose is broken down using oxygen to provide energy for the cells.

Question 21

Where does respiration take place?

Answer 21

In the mitochondria in the cell cytoplasm.

Question 22

What is aerobic respiration?

Answer 22

The breakdown of glucose to make energy using oxygen.

Question 23

What is the word and symbol equation for aerobic respiration?

Answer 23

Glucose + oxygen → carbon dioxide + water

C6H12O6 + 6O2 → 6CO2 + 6H2O

Question 24

What is anaerobic respiration?

Answer 24

The breakdown of glucose to make energy without using oxygen.

As the oxidation of glucose is incomplete, lactic acid is formed.

Question 25

What is the word equation for anaerobic respiration in muscle cells?

Answer 25

Glucose → lactic acid

Question 26

What is the word equation for anaerobic respiration in plants and yeast cells?

Answer 26

Glucose → ethanol + carbon dioxide

Question 27

What is fermentation? What is fermentation used for?

Answer 27

***Fermentation is anaerobic repetition in yeast cells.*** In **bread-making**, it’s the **carbon dioxide** from fermentation that makes bread **rise**. In **beer** and **wine-making**, it’s the fermentation process that produces **alcohol**.

Question 28

Why do you respire more when you exercise?

Answer 28

Muscles need energy from respiration to contract. When you exercise you need **more energy** because your **muscles contract more** frequently.

Question 29

Why does anaerobic respiration occur when exercising?

Answer 29

During exercise **respiration** in cells **increases** and they need more oxygen. Eventually your body will **not supply oxygen** to your muscles **quickly enough** so they start **anaerobic respiration.** This builds up **lactic acid** in the muscles, which is painful.

Question 30

What are the two ways lactic acid is removed from the muscles?

Answer 30

- Oxygen reacts with the lactic acid to form carbon dioxide and water. - The blood that enters your muscles transports the lactic acid to the liver where it is converted back to glucose.

Question 31

What is an oxygen debt?

Answer 31

The amount of extra oxygen your body needs to react with the build up of lactic acid and remove it from the cells. This means you have to keep breathing for a while after you stop, to get more oxygen into your blood, which is transported to the muscle cells.

Question 32

During exercise, why does heart rate increase?

Answer 32

• Blood is pumped around faster • Respiration occurs faster • More oxygen needs to be supplied • More glucose needs to be supplied • More CO2 needs to be removed • More lactic acid needs to be removed

Question 33

During exercise, why does rate and depth of breathing increase?

Answer 33

Respiration occurs faster to release energy for muscle contraction More oxygen is supplied to respiring cells More carbon dioxide is removed

Question 34

During exercise, why do arteries dilate?

Answer 34

To supply more blood to the muscles

Question 35

What is the pulse?

Question 36

What is metabolism?

Answer 36

The sum of all the reactions that happen in a cell or the body.

Question 37

What are the 2 types of metabolic reactions?

Answer 37

***Anabolic = synthesis reactions*** • endothermic • controlled by enzymes • join smaller molecules to create larger molecules ***Catabolic = breakdown reactions*** • exothermic • break down larger molecules into smaller molecules

Question 38

(What are anabolic reactions?) What are examples of anabolic reactions in both plants & animals?

Answer 38

***Anabolic = synthesis reactions*** • endothermic • controlled by enzymes • join smaller molecules to create larger molecules Examples: • glucose to form cellulose (plants) • glycogen to form starch • glycerol + fatty acids to form lipids • glucose + nitrate ions to form amino acids • amino acids to form proteins

Question 39

What are examples of catabolic reactions in both plants & animals?

Answer 39

***Catabolic = breakdown reactions*** • exothermic • break down larger molecules into smaller molecules Examples: • (in respiration) glucose to energy • (in digestion) proteins to amino acids • excess amino acids to urea (excreted as urine)