bioenergetics

Question 1

how is glucose used (in plants) for making amino acids?

Answer 1

it is combined with nitrate ions (absorbed from the soil) to make amino acids which are then made into proteins

Question 2

why is glucose turned into oils and fats in plants?

Answer 2

for storing in seeds

Question 3

how/why is glucose stored as starch in plants?

Answer 3

glucose is turned into starch and stored in roots stems and leaves ready for use when photosynthesis is not happening ( eg winter)
starch is insoluble which makes it better for storing than glucose - a cell with lots of glucose would draw lots of water in and swell up

Question 4

what 3 factors affect photosynthesis?

Answer 4

light, co2 concentration and temperature

Question 5

at night what is the limiting factor in photosynthesis?

Answer 5

light

Question 6

when it’s winter what is often the limiting factor in photosynthesis?

Answer 6

temperature

Question 7

when it’s warm and bright what is normally the limiting factor for photosynthesis?

Answer 7

Co2 concentration

Question 8

what part of a plant could be a limiting factor in photosynthesis?

Answer 8

chlorophyll

Question 9

what can affect the amount of chlorophyll in a plant?

Answer 9

• disease

- environmental stress (eg lack of nutrients)

Question 10

describe how light intensity effects the rate of photosynthesis

Answer 10

as the light level increases, the rate of photosynthesis increases steadily until a certain point
beyond that point the level of light won’t make a difference because either CO2 or temperature will become the limiting factor

Question 11

how can you increase light intensity in a lab?

Answer 11

move the lamp closer or further away

Question 12

when investigating light intensity’s effect on photosynthesis, in order to get a graph that shows a consistent incline and then levels of, what equipment should you use?

Answer 12

a light meter to measure light intensity

Question 13

describe how co2 concentration affects the rate of photosynthesis?

Answer 13

amount of co2 will only increase the rate of photosynthesis up until a point , and then the rate no longer increases showing co2 is no longer w limiting factor

Question 14

usually if the limiting factor in photosynthesis is temperature it’s because it’s too low - why?
what happens if it gets too hot?

Answer 14

• enzymes needed for photosynthesis work slower at colder temperatures
• enzymes needed for photosynthesis are damaged

Question 15

at what temperature does the enzymes of a plant denature at?

Answer 15

45 degrees

Question 16

what does the inverse square law mean

Answer 16

if you halve the distance the light intensity will be 4 times greater, and if you third the distance the light intensity will be nine times. greater

Question 17

light intensity =

Answer 17

1/d^2

Question 18

why are greenhouses the most common way to create the ideal environment for plants to grow in?

Answer 18

• greenhouses help trap the suns heat, and make sure the temperature doesn’t become the limiting factor
• in the winter a farmer may use a heater as well to keep the temperature level ideal
• in summer them may use shades and ventilation to cool things down
• commercial farmers often supply artificial blight after the sun goes down

Question 19

how may a farmer increase the concentration of co2 in a greenhouse?

Answer 19

by a paraffin heater used to heat the greenhouse, as paraffin burns it makes carbon dioxide as a by-product

Question 20

what can farmers add to the soil in his greenhouse to provide all the minerals needed for healthy growth?

Answer 20

fertiliser

Question 21

define respiration

Answer 21

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

Question 22

what kind of reaction is respiration?

Answer 22

exothermic

Question 23

what are 3 examples of how organisms use their energy transferred by respiration?

Answer 23

1) to build up larger molecules from smaller ones ( eg proteins from amino acids)
2) to allow muscles to contact, so animal can move about
3) in mammals and birds it’s used to maintain a constant body temperature in colder surroundings

Question 24

what is metabolism?

Answer 24

the sun of all the chemical reactions happening in an organism

Question 25

give 3 examples of metabolic reactions when large molecules are made from smaller molecules e

Answer 25

1) small glucose molecules are joined together in reactions to form: starch, glycogen and cellulose
2) 1 molecule of glycerol and 3 molecules of fatty acids form lipids
3) glucose combined with nitrate ions to make amino acids, which are then made into proteins

Question 26

give 2 example of metabolic reactions when large molecules are broken down into smaller ones

Answer 26

1) glucose is broken down in respiration

2) excess protein is broken down in a reaction to produce urea

Question 27

what is aerobic respiration?

Answer 27

• respiration using oxygen

Question 28

where does most of aerobic respiration happen? ( part of cell)

Answer 28

mitochondria

Question 29

what is the word equation for aerobic respiration?

Answer 29

glucose + oxygen -> carbon dioxide + water

Question 30

what is anaerobic respiration?

Answer 30

respiration without oxygen, an incomplete breakdown of glucose creating lactic acid

Question 31

when does your body start to do anaerobic respiration as well as aerobic?

Answer 31

when you do vigorous exercise and your body can’t supply enough oxygen to your muscles

Question 32

why is anaerobic respiration only useful in emergencies?

Answer 32

because it doesn’t transfer as much energy as aerobic respiration because the glucose isn’t full oxidised

Question 33

what is the word equation of anaerobic respiration in plants and yeast cells?

Answer 33

glucose -> ethanol + carbon dioxide

Question 34

anaerobic respiration in yeast cells is called what?

Answer 34

fermentation

Question 35

how is fermentation used in the food and rinks industry?

Answer 35

to make bread and alcoholic drinks

bread making: co2 makes bread rise
alcohol: fermentation process that produces the alcohol

Question 36

why do you need more energy when you exercise?

Answer 36

because your muscles contract more frequently than normal

Question 37

what changes happen in your body when you exercise?

Answer 37

• breathing rate and volume increases to get more oxygen in the blood
• heart rate increases to get the oxygenated blood around your body faster, removing co2 quickly at the same time

Question 38

why is lactic acid not ideal?

Answer 38

when it builds up it’s painful

Question 39

what can long periods of exercise lead to?

Answer 39

muscle fatigue - they muscles get tired and stop contacting efficiently

Question 40

what is an oxygen debt?

Answer 40

the amount of extra oxygen your body needs to react with the build up of lactic acid and remove it from the cells, oxygen reacts with the glucose to form harmless co2 and water

Question 41

why do you keep brushing hard for a while after you stop exercising?

Answer 41

to get more oxygen to your blood which is transported to your muscle cells

Question 42

how is the liver involved with dealing with lactic acid?

Answer 42

the blood that enters your muscles transports the acid to the liver, where it is then converted back to glucose