food production

Question 1

what conditions can be manipulated in a glasshouse

Answer 1

Artificial heating (enzymes controlling photosynthesis can work faster at slightly higher temperatures - only used in temperate countries such as the UK)
Artificial lighting (plants can photosynthesise for longer)
Increasing carbon dioxide content of the air inside (plants can photosynthesise quicker)
Regular watering

Question 2

what farmers in tropical countries may consider to manipulate?

Answer 2

need to be ventilated to release hot air and avoid temperatures rising too high, which could cause the denaturation of the enzymes controlling the photosynthesis reaction

Question 3

polyethene tubes

Answer 3

large plastic tunnels that cover crops

Question 4

polythunels uses

Answer 4

They can protect crops grown outside from the effects of the weather, including excessive wind, rain and extreme temperatures
They also increase the temperature slightly inside the tunnel
They can prevent the entry of pests that can damage plants or diseases that can kill plants

Question 5

3 limiting factors of photosynthesis

Answer 5

Temperature
Light intensity
Carbon dioxide concentration

Question 6

how does temperature affect the rate of photosynthesis

Answer 6

.temperature increases the rate of photosynthesis
.this is only to a certain point as enzymes begin denature and the rate of reaction decreases.

Question 7

how does light affect the rate of photosynthesis

Answer 7

more light, faster rate of photosynthesis
This trend will continue until some other factor required for photosynthesis prevents the rate from increasing further because it is now in short supply

Question 8

how does carbon dioxide affect the rate of photosynthesis

Answer 8

.more carbon dioxide faster rate of photosynthesis
.This trend will continue until some other factor required for photosynthesis prevents the rate from increasing further because it is now in short supply

Question 9

fertilisers

Answer 9

increase the amount of key nutrients in the soil for crop plants, therefore plants can grow more larger and healthy which increases crop yield

Question 10

pesticides

Answer 10

these chemicals kill off unwanted insects and weed species, meaning that there is less damage done to crop plants by insects, as well as reducing competition from other plant species, which increases yields

Question 11

organic fertilisers

Answer 11

manure and compost

Question 12

chemical fertilisers

Answer 12

dry granules or can be sprayed on in liquid form
They mainly provide crop plants with nitrogen, phosphorus and potassium:

Question 13

nitrogen in fertilisers

Answer 13

Absorbed in the form of nitrates
Needed to make amino acids which are the building blocks of proteins
Lack of nitrogen causes weak growth and yellowing of the leaves of plants

Question 14

potassium in chemical fertilisers

Answer 14

Absorbed in the form of various compounds of potassium
Allows enzyme reactions to take place to produce ATP in respiration as well as being needed for the enzymes involved in photosynthesis
Lack of potassium can cause poor growth of flowers and fruits, as well as brown spots on leaves

Question 15

phosphorus in fertilisers

Answer 15

Absorbed in the form of phosphates
Needed to make DNA and cell membranes
Lack of phosphorus can cause poor root growth and discoloured leaves

Question 16

types of pesticides

Answer 16

Insecticides kill insect pests
Herbicides kill plant pests
Fungicides kill fungal pests

Question 17

advantages of pesticides

Answer 17

easily accesible
immediate effect
kills entire population of pests

Question 18

disatvantages of pesticides

Answer 18

organisms can develop resistance
can kill beneficial organisms as they are non specific
do not break down
need to be repeatedly applied

Question 19

advantages of biological control

Answer 19

no pollution
no resistance
can target specific species
long lasting
does not need to be repeatedly applied

Question 20

disatvantages of biologocal control

Answer 20

may eat other organisms instead of pests
takes longer to be effective
cannot kill entire population
may not to new environment or may move out of area
may become a pest itself

Question 21

bread making steps

Answer 21

Yeast will respire anaerobically if it has access to plenty of sugar, even if oxygen is available
This is taken advantage of in bread making, where the yeast is mixed with flour and water
The yeast produces enzymes that break down the starch in the flour, releasing sugars that can then be used by the yeast for anaerobic respiration
The carbon dioxide produced by the yeast during anaerobic respiration is trapped in small air-pockets in the dough, causing the dough to rise (increase in volume)
The dough is then baked in a hot oven to form bread
During baking, any ethanol produced by the yeast (as a waste product of anaerobic respiration) is evaporated in the heat
This is why bread doesn’t contain any alcohol
The yeast is killed by the high temperatures used during baking
This ensures there is no further respiration by the yeast
Once cooled, the bread is ready to be eaten

Question 22

anaerobic respiration formula

Answer 22

glucose = ethanol and carbon dioxide
C6H12O6 = 2C2H5OH and 2CO2

Question 23

why are bacteria useful in yogurt production?

Answer 23

.capable of producing complex molecules
.reproduce rapidly

Question 24

how to calculate dry mass

Answer 24

pass content through filter paper
heat filter paper
wight

Question 25

why are plants selectively bred?

Answer 25

Disease resistance in food crops
Increased crop yield
Hardiness to weather conditions (eg. drought tolerance)
Better tasting fruits
Large or unusual flowers

Question 26

what can selective breeding lead to?

Answer 26

it can lead to inbreeding

Question 27

what does inbreeding result in?

Answer 27

This results in a reduction in the gene pool – this is a reduction in the number of alleles (different versions of genes) in a population
As inbreeding limits the size of the gene pool, there is an increased chance of:
Organisms inheriting harmful genetic defects
Organisms being vulnerable to new diseases (there is less chance of resistant alleles being present in the reduced gene pool)