B4: Bioenergetics

Question 1

What is the word equation for photosynthesis?

Answer 1

carbon dioxide + water → glucose + oxygen

Question 2

What is the symbol equation for photosynthesis?

Answer 2

CO2 + H2O → C6H12O6 + O2

Question 3

What sort of reaction is photosynthesis?

Answer 3

endothermic (takes in energy)

Question 4

What is a limiting factor?

Answer 4

a factor that prevents a reaction from going any faster

Question 5

How does temperature affect the rate of photosynthesis?

Answer 5

-directly proportional because more energy is supplied
-as the temperature reaches 45°C, rate of photosynthesis drops to zero because the enzymes controlling the reaction have denatured

Question 6

How does carbon dioxide concentration affect the rate of photosynthesis?

Answer 6

-directly proportional because it is needed in the reaction
-after reaching a certain point, an increase in carbon dioxide has no effect because it is no longer the limiting factor

Question 7

How does light intensity affect the rate of photosynthesis?

Answer 7

-directly proportional because more energy is supplied
-after a certain point, it has no effect because it is no longer the limiting factor

Question 8

How does chlorophyll concentration affect the rate of photosynthesis?

Answer 8

-does not vary in the short term but may change if plants are grown in soil without enough minerals to make chlorophyll

Question 9

What is the inverse square law?

Answer 9

when a light source is moved to double the distance then the light intensity reduces by a quarter

Question 10

(there’s 5)

How might the glucose produced in photosynthesis be used by the plant?

Answer 10

-used in respiration for energy
-changed into insoluble starch which is stored in the stem, leaves or roots
-changed into fat or oil which is also stored (e.g. in seeds)
-changed into cellulose to strengthen cell walls
-changed into amino acids to produce proteins for growth and enzymes (also use nitrate ions from the soil)

Question 11

What sort of reaction is respiration?

Answer 11

exothermic (produces energy)

Question 12

What do organisms use the energy from respiration for?

Answer 12

-for chemical reactions to build larger molecules
-for movement
-to keep warm

Question 13

What is the word equation for aerobic respiration?

Answer 13

glucose + oxygen → carbon dioxide + water

Question 14

What is the symbol equation for aerobic respiration?

Answer 14

C6H12O6 +O2 → CO2 + H2O

Question 15

What is anaerobic respiration?

Answer 15

respiration that takes place without oxygen, producing energy and lactic acid

Question 16

What happens in anaerobic respiration?

Answer 16

glucose is not entirely broken down so produces much less energy than aerobic respiration

Question 17

What is the word equation for anaerobic respiration in animals?

Answer 17

glucose → lactic acid

Question 18

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

Answer 18

glucose → ethanol + carbon dioxide

Question 19

What could happen inside of muscles during periods of vigorous activity?

Answer 19

they may not get supplied with enough oxygen, causing anaerobic respiration to take place. this causes a build up of lactic acid and oxygen debt

Question 20

What happens as a result of a build up of lactic acid?

Answer 20

muscles start to hurt and they stop contracting efficiently (lactic acid is a poison so must be removed quickly)

Question 21

What happens after exercise?

Answer 21

blood flowing through the muscles transport the lactic acid to the liver where it is converted back to glucose.

Question 22

What is the oxygen debt?

Answer 22

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

Question 23

What is metabolism?

Answer 23

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