bioenergetics

Question 1

what is photosynthesis?

Answer 1

The process by which plants synthesise glucose using light energy from the Sun.

Light energy is converted into chemical energy

Question 2

where does photosynthesis take place?

Answer 2

Within chloroplast in leaf Palaside cells. They contain chlorophyll, a pigment which absorbs light energy.

Question 3

State the equations for photosynthesis

Answer 3

6co2 + 6H2o —-> C6H12O6 + 6O2

Question 4

Is photosynthesis an endothermic or exothermic reaction and why?

Answer 4

Endothermic energies transferred from the environment to the chloroplast by light

Question 5

How can you show that a plant gives off oxygen during photosynthesis?

Answer 5

using a water plant, collect gas bubbles produced during photosynthesis. The gas will relight a glowing splint as it contains oxygen

Question 6

Give examples of leaf adaptations which maximise the rate of photosynthesis

Answer 6

broadleaves – maximise surface area
Fin leaves – short diffusion distance
Chlorophyll present – trap light energy
Veins – transport water to leaves via xylem, remove photosynthesis products by phloem
airspaces– allows CO2 to enter an O2 to leave
Guard cells – control opening of stomata for gaseous exchange preventing water loss 

Question 7

what are the four main factors that affect the rate of photosynthesis?

Answer 7

Temperature, light intensity, carbon dioxide concentration, amount of chlorophyll

Question 8

how does the temperature affect the rate of photosynthesis?

Answer 8

Increasing the temperature increases the rate of photosynthesis as the kinetic energy of the particles is increased. The rate decreases past a certain temperature as enzymes become denatures.

Question 9

how does light intensity affect the rate of photosynthesis?

Answer 9

Increasing the light intensity increases the rate of photosynthesis until another factor becomes limited

Question 10

how does carbon dioxide concentration affect the rate of photosynthesis?

Answer 10

Increasing the carbon dioxide concentration increases the rate of photosynthesis ( until another factor becomes limiting ) as CO2 is required to make glucose


Question 11

How does the amount of chlorophyll affect the rate of photosynthesis?

Answer 11

decreasing the amount of chlorophyll(eg due a to lack of magnesium) decreases the rate of photosynthesis as chlorophyll is required to absorb light energy

Question 12

what is a limiting factor?

Answer 12

An environmental factor which can restrict the rate of photosynthesis
eg light intensity

Question 13

explain how you can calculate the rate of photosynthesis by measuring oxygen production

Answer 13

set up a bubble potometer apparatus (pondweed in a sealed tube of water, attached to a capillary tube and a gas syringe )

Oxygen gas produced causes the bubbles in the capillary tube to move the distance moved by the bubble is used to calculate the volume of oxygen produced 

Question 14

How can farmers use their knowledge of limiting factors to increase their profits?

Answer 14

They can control temperature, light intensity and CO2 concentration to achieve the fastest possible rate of photosynthesis, leading to greater yield

Question 15

State the law which describes the relationship between the distance of light source from a plant and light intensity

Question 16

State five uses of glucose produced during photosynthesis

Answer 16

Respiration
Starch for Storage
Cellulose for Strength
Amino acid and protein synthesis (combined with nitrates)
Lipids for energy storage and seeds

Question 17

What is aerobic respiration?

Answer 17

An exothermic reaction in which glucose reacts with oxygen to release energy which can be used by cells

Question 18

what are the equations for aerobic respiration?

Answer 18

C6H12O6 + 6O2 ———> 6CO2 + 6H2O

Question 19

where does aerobic respiration take place?

Answer 19

Mitochondria

Question 20

Why do organisms require the energy release by respiration?

Answer 20

synthesis of larger molecules
Muscle contraction
Maintenance of body temperature
Active transport

Question 21

What is an anaerobic respiration?

Answer 21

An exothermic reaction in which glucose is broken down to release energy in the absence of oxygen

Question 22

what is the equation for anaerobic respiration?

Answer 22

glucose —-> lactic acid (+energy)

Question 23

Why is anaerobic respiration less efficient than aerobic respiration?

Answer 23

Glucose is not completely broken down, so less energy is transferred

Question 24

why can anaerobic respiration lead to muscle fatigue?

Answer 24

Lactic acid buildup in muscles, preventing efficient contraction

Question 25

What is an oxygen debt

Answer 25

The amount of oxygen needed to convert lactic acid into back into glucose after anaerobic respiration

Question 26

what is fermentation?

Answer 26

A type of anaerobic respiration that occurs in yeast cells

Question 27

what is the equation for fermentation?

Answer 27

glucose —-> ethanol + carbon dioxide (+energy)

Question 28

why is the fermentation reaction important?

Answer 28

It is used in the production of bread and alcoholic drinks

Question 29

What are the differences between aerobic and anaerobic respiration?

Answer 29

aerobic requires oxygen; anaerobic does not Aerobic produces CO2 and water: anaerobic produces lactic acid or ethanol and CO2 Aerobic transfers, a greater amount of energy

Question 30

how do muscles store glucose?

Answer 30

As glycogen

Question 31

What changes take place when muscular activity increases in the body?

Answer 31

heart rate increases in arteries dilate – increases flow oxygenated blood to the muscles Breathing rate increases and breathing is deeper – increases the rate of gaseous exchange stores glycol is converted back into glucose

Question 32

How is lactic acid transported away from the muscles?

Answer 32

blood flow through the muscles transports lactic acid to the liver, where it is oxidised back to glucose

Question 33

What is metabolism?

Answer 33

The sum of all the reactions that take place in a cell or an organism

Question 34

How do cells use energy transferred by respiration?

Answer 34

To continuously carry out enzyme controlled processes which lead to the synthesis of new molecules

Question 35

give examples of metabolic reactions

Answer 35

Glucose into starch/glycogen/cellulose Glycerol and fatty acids into lipids Glucose and nitrate ions into amino acids Photosynthesis Respiration Breakdown of excess proteins into urea