Manipulation of food species (agroecosystems)

Question 1

name the 4 types of genetic manipulation

Answer 1

1. selective breeding
2. crossbreeding
3. asexual reproduction
4. genetic engineering/transgenics

Question 2

describe selective breeding + example

Answer 2

choosing parents with desirable characteristics together = offspring with more desirable characteristics
i.e. belgian blue = more meat

Question 3

give 2 advantages of selective breeding

Answer 3

1. remove undesirable characteristics

2. enhance desirable characteristics

Question 4

give 2 disadvantages of selective breeding

Answer 4

1. risk of inbreeding (small gene pool)

2. reduce genetic diversity

Question 5

describe crossbreeding + example

Answer 5

mating parents of 2 different breeds/varieties

i.e. Zebu with Ayrshire cattle = high milk yield + tolerate heat

Question 6

give 2 advantages of crossbreeding

Answer 6

1. lower risk of inbreeding

2. leads to hybrid vigour or heterosis (increased function of hybrid offspring)

Question 7

give 2 disadvantages of crossbreeding

Answer 7

1. could lead to serious genetic issues

2. characteristics sometimes not predictable

Question 8

describe asexual reproduction in plants

Answer 8

vegetative propagation: new plant produced from sections of plant i.e. stem

Question 9

describe asexual reproduction in animals

Answer 9

cloning:
1. egg cell nucleus taken out
2. replaced with donor nucleus (fused)
3. embryo formed
4. embryo placed in mother
5 cloned organism genetically identical to the donor who gave nucleus

Question 10

give 4 advantages to asexual reproduction (both plants/animals)

Answer 10

1. genetically identical to parent
2. characteristics predictable
3. high survival rate
4. can replace valuable organisms with identical ones

Question 11

give 2 disadvantages to asexual reproduction for both plants/animals

Answer 11

1. no opportunity to improve genetic qualities

2. more susceptible to infection/disease

Question 12

give 1 disadvantage to asexual reproduction for plants

Answer 12

fewer offspring produced than by sexual reproduction

Question 13

define transgenics

Answer 13

transfer of genes (of desirable characteristics) from species where they are naturally found to another species where they are not

Question 14

give 4 advantages of GM/transgenics

Answer 14

1. genes introduced that could’ve never been gained via selective breeding
2. increase resistance to pests (reduce pesticides)
3. increase yield
4. a single characteristic introduced

Question 15

give successful example of GM/transgenics

Answer 15

golden rice: genes from daffodile + a soil bacterium = increased vit. A in rice

Question 16

give the 5 disadvantages of GM/transgenics

Answer 16

1. pollen transfer to non GM crops
2. transfer of resistant gene to bacteria
3. reduction in native crop diversity
4. link to food allergies
5. increased costs for farmers

Question 17

give an unsuccessful example of GM/transgenics

Answer 17

Bt crops: genes transferred from soil bacterium into corn crops (toxin produced to kill insects) = killed non-target species i.e. monarch butterfly

Question 18

definition of yield

Answer 18

amount of crop per hectare

Question 19

define energy subsidies

Answer 19

any input that increases productivity but requires the use of energy from fossil fuels

Question 20

give 3 examples of energy subsidies

Answer 20

1. pumping of irrigation H2O
2. fuel for machinery
3. manufacture of nitrate fertilisers/pesticides

Question 21

T or F organic and subsistence farming are not labour intensive

Answer 21

false: very labour intensive!!

Question 22

explain intensive farming

Answer 22

large amounts of inputs over a small area of land yield high per unit area
labour: low, Capital: high, Artificial fertilisers: high

Question 23

which type of farming has the highest output?

Answer 23

intensive farming

Question 24

which type of farming has the lowest productivity?

Answer 24

extensive

Question 25

explain extensive farming

Answer 25

maximise yield by spreading available inputs over a large area of land
labour + capital + artificial fertilisers = low

Question 26

what is the law of diminishing returns?

Answer 26

• increase the inputs, extra yield increase gets smaller

shows the link between efficiency + productivity

Question 27

what are energy ratios?

Answer 27

measure of efficiency showing no. of food energy produced per unit of energy input

Question 28

a system with high yields per unit energy has a higher….

Answer 28

energy ratio

Question 29

a system with high productivity normally has high subsidies and so has low….

Answer 29

energy ratio

Question 30

what is the formula to calculate energy ratio?

Answer 30

outputs/inputs

Question 31

what is the formula to calculate energy efficiency (%)?

Answer 31

outputs/inputs x 100

Question 32

name the 3 reasons why monocultures can increase productivity

Answer 32

1. easy planting/weeding/harvesting etc.
2. favours mechanisation (low labour)
3. offers economies of scale (saving gained by increase level of production)

Question 33

name the 4 disadvantages of monoculture

Answer 33

1. reduces biodiversity (less niches)
2. increase risk of soil erosion
3. may lead to exhaustion of particular soil nutrients
4. worst pest epidemics

Question 34

if you have a high stocking/crop density________ is increased although can cause stress + _____ have greater effect

Answer 34

productivity, disease

Question 35

definition of an autotroph

Answer 35

an organism which makes own nutrition from simple, inorganic substances i.e. producers

Question 36

definition of an heterotroph

Answer 36

an organism which gains energy from eating other organisms

Question 37

name the 3 ways to reduce food chain losses

Answer 37

1. control movement
2. temp control
3. species selection

Question 38

how does control of movement reduce food chain losses? + how is this done?

Answer 38

reduce movement, reduce respiration = more energy converted to growth i.e. place in cages

Question 39

how does temp control reduce food chain losses?

Answer 39

keep organism warm, reduce energy lost as heat = more energy converted to growth

Question 40

definition of food conversion ratio

Answer 40

measure of mass of food needed to produce a given mass of livestock growth

Question 41

why is species selection important in reducing food chain losses?

Answer 41

• different species have different food conversion ratios

- lower the FCR = better conversion of food into biomass