bioenergetics

Question 1

what is photosynthesis?

Answer 1

an endothermic reaction where light energy is transferred by chloroplasts to produce glucose

Question 2

what is the word equation for photosynthesis?

Answer 2

carbon dioxide + water –> glucose + oxygen

Question 3

what is the symbol equation for photosynthesis?

Answer 3

CO2+H2O –> C6H12O6 +O2

Question 4

where in the plant does photosynthesis take place?

Answer 4

inside chloroplasts in plant cells

Question 5

do all plant cells have chloroplasts?

Answer 5

no, only the ones that recieve light

Question 6

which plant cells have the most chloroplasts?

Answer 6

the palisade mesophyll cells in the leaves

Question 7

what factors affect the rate of photosynthesis?

Answer 7

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

Question 8

why does temperature affect photosynthesis?

Answer 8

photosynthesis is a process that uses enzymes. if the enzymes get warmer, photosynthesis happens at a faster rate, but if the enzymes get too hot, they will denature and photosynthesis will stop

Question 9

what other organisms photosynthesise?

Answer 9

algae (pondweed and seaweed), as well as some bacteria. if there is chloroplast, it will absorb light energy and photosynthesise

Question 10

what is the inverse square law?

Answer 10

the light energy reaching a certain point is equal to the inverse square of the distance to that point. we can turn distance into light intensity using 1/(d squared).

Question 11

why do people care about the rate of photosynthesis?

Answer 11

anyone producing food crops will want to maximise profit. adding light, carbon dioxide, or heat into a greenhouse will give faster growth but may cost more, so may not be worth doing.

Question 12

what is glucose produced in photosynthesis used for?

Answer 12

respiration by all living cells. also some is converted into starch, fats/oils, cellulose and amino acids

Question 13

why do plants store glucose as starch?

Answer 13

• starch is insoluble, so doesnt affect osmosis
• more compact, so easier to store large amounts
• used by cells as a source of glucose for respiration
  when it is dark

Question 14

why do plants convert glucose to oils?

Answer 14

seeds have oils stored in them as the energy supply for the new plant to start to grow (germinate)

Question 15

why do plants convert some glucose to cellulose?

Answer 15

cell walls are made from cellulose. it is strong and helps to support the plant. all plant cells have cell walls.

Question 16

why do plants convert some glucose to amino acids?

Answer 16

• amino acids are the building blocks of protein (for
  growth and repair)
• plants need amino acids for protein synthesis
  (plants are responsible for producing many of the
  amino acids we rely on too)

Question 17

what else do plants need to turn glucose into amino acids?

Answer 17

glucose only contains the elements CHO. amino acids contain CHON. plants need nitrate ions from the soil to make amino acids.

Question 18

what is respiration?

Answer 18

an exothermic reaction where energy is released from glucose molecules. it happens continuously in all living cells

Question 19

why do living cells need to respire?

Answer 19

living cells need an energy supply for all the processes they carry out (eg chemical reactions, keeping warm and movement). without this energy supply, cells would die

Question 20

what are the 2 types of respiration?

Answer 20

aerobic (with oxygen) anaerobic (without oxygen)

Question 21

what is the word equation for aerobic respiration?

Answer 21

glucose + oxygen –> carbon dioxide + water

Question 22

what is the word equation for anaerobic respiration?

Answer 22

glucose –> lactic acid

Question 23

is all anaerobic respiration the same?

Answer 23

no, the equation is different for muscles and plants/ yeast

Question 24

whats the word equation for anaerobic respiration in plants/yeast?

Answer 24

glucose –> ethanol + carbon dioxide

Question 25

why is anaerobic respiration sometimes called fermentation?

Answer 25

fermentation is just anaerobic respiration in plants and yeast, and it is economically important as it is how we produce bread and alcoholic drinks

Question 26

what happens to respiration when we exercise?

Answer 26

respiration rate increases as our cells require more energy

Question 27

what happens to heart rate when respiration increases?

Answer 27

heart rate increases so that blood circulates faster. this helps supply more oxygen and glucose to muscle cells (and removes lactic acid more quickly too)

Question 28

what happens to breathing rate when respiration increases?

Answer 28

breathing rate increases so that more oxygen enters the blood. this also helps supply more oxygenated blood to the muscle cells (and removes carbon dioxide more quickly too)

Question 29

what happens to breath volume when respiration increases?

Answer 29

each breath volume is bigger as we breathe more deeply during exercise. this also helps supply more oxygenated blood to muscle cells

Question 30

what if not enough oxygen gets to the muscle cells?

Answer 30

anaerobic respiration will start to take place (as well as aerobic, with whatever oxygen is delivered to muscle cells) lactic acid will start to build up, creating oxygen debt.

Question 31

what is the problem with lactic acid building up?

Answer 31

cells become fatigued if there is too much lactic acid. they stop contracting efficiently

Question 32

what happens to the lactic acid?

Answer 32

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 oxygen needed to react with the lactic acid to get rid of it.

Question 33

what is a metabolism?

Answer 33

the sum of all reactions in a cell of body.

Question 34

what is the energy transferred from respiration used for?

Answer 34

building up new molecules using enzymes inside the cells

Question 35

does metabolism include carbohydrate production?

Answer 35

yes... converting glucose to starch, cellulose, and glycogen.

Question 36

does metabolism include lipid production?

Answer 36

yes... joining 3 fatty acids and 1 glycerol to make a lipid molecule

Question 37

does metabolism include protein production?

Answer 37

yes... using glucose and nitrate ions to form amino acids, then joining them to synthesise proteins

Question 38

what else does metabolism include?

Answer 38

respiration itself is a metabolic process. also excess proteins are broken down in the liver to form urea which is excreted.