B1 - Bioenergetics

Question 1

Aerobic respiration:

Answer 1

A form of respiration that uses oxygen to release energy
from molecules like glucose - represented by the following word equation: glucose + oxygen —–> carbon dioxide +water

Question 2

Anaerobic respiration:

Answer 2

A form of respiration that releases energy from molecules
like glucose without using oxygen - represented by the following word equation:
glucose —–> lactic acid

Question 3

Cellular respiration

Answer 3

An exothermic reaction which is continuously occurring in
living cells

Question 4

Limiting factor

Answer 4

A factor that limits the rate of a reaction when there is not enough
of it.

Question 5

Photosynthesis:

Answer 5

An endothermic reaction in which energy is transferred from the
environment to the chloroplasts by light

Question 6

Oxygen debt:

Answer 6

The amount of extra oxygen the body needs after exercise to
react with the accumulated lactic acid and remove it from the cells.

Question 7

what is photosynthesis

Answer 7

the process by which plants synthesise glucose using light energy from the sun. Light energy is converted into chemical energy

Question 8

where does photosynthesis take place

Answer 8

within chloroplasts in leaf palisade cells. They contain chlorophyll , a pigment which absorbs light energy

Question 9

state the word and symbol equation for photosynthesis

Answer 9

1)6CO2 + 6H2O → C6H12O6 + 6O2.
2)Carbon dioxide + water —- (with light energy) —-> glucose + oxygen gas.

Question 10

is photosynthesis an endothermic or exothermic reaction and why?

Answer 10

endothermic - energy is transferred from the environment to chloroplasts by light

Question 11

how can you show that a plant gives off oxygen during photosynthesis

Answer 11

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

Question 12

give examples of leaf adaptations which maximise the rate of photosynthesis

Answer 12

1) broad leaves - maximises surface area
2) thin leaves - short diffusion distance
3)chlorophyll present - trap light energy
4)veins - transport water to leaves via xylem , remove photosynthesis products via phloem
5) air spaces - allow CO2 to enter and 02 to leave

Question 13

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

Answer 13

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

Question 14

how does the temperature affect the rate of photosynthesis

Answer 14

increasing the temperature increases the rate of photosynthesis as the kinetic energy of particles is increased. The rate decreases past a certain temperature as enzyme become denatured

Question 15

how does light intensity affect the rate of photosynthesis

Answer 15

increasing the light intensity increases the rate of photosynthesis until another factor becomes limiting

Question 16

how does carbon dioxide affect the rate of photosynthesis

Answer 16

increasing the carbon dioxide concentration increases the rate of photosynthesis as co2 is required to make glucose

Question 17

how does the amount of chlorophyll affect the rate of photosynthesis

Answer 17

decreasing the amount of chlorophyll decreases the rate of photosynthesis as chlorophyll is required to absorb light energy

Question 18

what is a limiting factor

Answer 18

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

Question 19

state 5 uses of glucose produced during photosynthesis

Answer 19

1) respiration
2) starch for storage
3) cellulose for strength
4) amino acid and protein synthesis
5)lipids for energy storage in seeds

Question 20

what is aerobic respiration

Answer 20

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

Question 21

what are the word and symbol equations for aerobic respiration

Answer 21

1)C6H120 +602 —->6C02+6H20
2)Glucose + oxygen → carbon dioxide + water + energy

Question 22

where does aerobic respiration take place

Answer 22

in the mitochondria

Question 23

why do organisms require the energy released by respiration

Answer 23

1) synthesis of larger molecules
2)muscle contraction
3)maintenance of body temperature
4) active transport

Question 24

what is anaerobic respiration

Answer 24

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

Question 25

what is the equation for anaerobic respiration

Answer 25

glucose —->lactic acid (+energy)

Question 26

why is anaerobic respiration less efficient than aerobic respiration

Answer 26

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

Question 27

why can anaerobic respiration lead to muscle fatigue

Answer 27

lactic acid (product for anaerobic respiration builds up in muscles , preventing efficient contraction

Question 28

what is an oxygen debt

Answer 28

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

Question 29

what is fermentation

Answer 29

a type of anaerobic respiration that occurs in yeast cells

Question 30

what is the equation for fermentation

Answer 30

glucose —> ethanol+ carbon dioxide (+energy)

Question 31

why is the fermentation reaction important

Answer 31

it is used in the production of bread and alcoholic drinks

Question 32

what are the differences between aerobic and anaerobic respiration

Answer 32

1) aerobic requires oxygen
2) aerobic produces C02 and water; anaerobic produces lactic acid or ethanol
3) aerobic transfers a greater amount of energy

Question 33

what changes take place when muscular activity increases in the body

Answer 33

1) heart rate increases and arteries dilate - increases flow of oxygenated blood to muscles
2) breathing rate increases and breathing is deeper - increases the rate of gaseous exchange
3) stored glycogen I converted back into glucose

Question 34

what is metabolism

Answer 34

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

Question 35

how do cells use the energy transferred by respiration

Answer 35

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

Question 36

give examples of metabolism

Answer 36

1)glycerol and fatty acids into lipids
2)photosynthesis
3) respiration
4) glucose and nitrate intno into amino acids