Unit Three - Sustainability and interdependence

Question 1

Explain what is meant by food security? (3)

Answer 1

the ability to access sufficient quality and quantity of food over an extended period of time

Question 2

Explain why there has been a major increase in concern about food security in recent years?

Answer 2

Increase in human population means an increase in food production

Question 3

Describe how two methods of improving food production from crops lead to increase in yield?

Answer 3

planting a greater area of crop and use fertilisers and ensure good supply of water.

Question 4

in terms of food security explain one benefit of using plants rather than livestock for human food.

Answer 4

crops are producers and livestock are consumers, therefore energy is lost between each trophic level of a food chain so greater number of people could be fedd using crops

Question 5

Explain the difference between the absorption spectrum of a pigment and the action spectrum of a green plant.

Answer 5

An absorption spectrum shows the extent to which each wavelength of light is absorbed by a pigment, an action spectrum shows the rate of photosynthesis by a whole plant at each wavelength.

Question 6

Describe the part played by carotenoid pigments in photosynthesis

Answer 6

Carotenoid pigments extend the range of wavelengths of light absorbed for photosynthesis and pass the energy onto chlorophyll

Question 7

Light energy absorbed by photosynthetic pigments excites electrons in the pigment molecules of the chloroplast
Describe the role of the excited electrons in photosynthesis.

Answer 7

Releases energy to generate ATP by ATP synthase

Question 8

During photosynthesis, G3P is produced when an intermediate substance is combined with hydrogen and phosphorylated by ATP.
Name the stage of photosynthesis which provides the hydrogen and ATP for this reaction and the intermediate substance involved.

Answer 8

Light dependant stage, 3-phosphoglycerate

Question 9

Explain how the conversion of 3-phosphoglycerate to G3P in the carbon fixation stage is dependant on chemical reactions in the light-dependant stage of photosynthesis.

Answer 9

Light-dependant stage produces the ATP and NADPH required to reduce 3PG into G3P.

Question 10

Describe the fate of G3P produced during the carbon fixation stage

Answer 10

The G3P is converted into glucose or can be used to regenerate RuBP

Question 11

Describe three fates of the glucose produced by photosynthesis

Answer 11

The glucose produced can be used in respiration synthesised to cellulose, converted into starch used in the synthesis of a variety of metabolites.

Question 12

Describe the changes in concentration of RuBP and G3P that would be expected to occur if an illuminated green plant cell’s source of carbon dioxide were removed

Answer 12

RuBP would increase and G3P would decrease

Question 13

Explain the role of breeders in supporting sustainable food production

Answer 13

breeders develop crops/animals with higher food yield, higher nutritional values, pest resistance and ability to thrive in particular environmental conditions

Question 14

explain the purpose of carrying out plant field trials

Answer 14

to compare the performance of plots of different varieties of crop plant
or
to compare how plots of one cultivar perform with a range of treatments application levels

Question 15

explain the need for replication and randomisation of treatments in a plant breeding field trial

Answer 15

Replication takes account of the variability within the sample and increase the reliability of the results; randomisation eliminates bias

Question 16

Explain the meaning of the term “inbreeding depression”

Answer 16

An increase in the effects of recessive deleterious alleles due to inbreeding

Question 17

Describe one method of maintaining a new crossbreed population that shows improved characteristics

Answer 17

The two parent breeds can be maintained to produce more crossbred animals showing the improved characteristics

Question 18

Describe the role of genomic sequencing in animal breeding programmes

Answer 18

individiuals with desirable genes can be identified and then used in breeding programmes

Question 19

describe the role of genomic sequencing in breeding programme to improve crop plants

Answer 19

single genes identified for desirable characteristics can be inserte into the genome of crop plants, creating genetically modified plants with improved characteristics

Question 20

Explain the advantage of producing a plant cultivar which has had a Bt toxin gene inserted into it’s genome

Answer 20

Produces its own pesticide and increases yield without need for pesticide application

Question 21

Explain the advantage of producing a plant cultivar which has had the glyphosate resistance gene inserted into it’s genome

Answer 21

Produces plant with herbicide tolerance and allows uses with herbicide to remove weeds but not the cultivar

Question 22

Describe the adaptations of annual plants that allow them to be successful weeds of crop plant

Answer 22

Rapid growth or complete life-cycle within a year, higher seed output, long-term seed vitality

Question 23

Describe the adaptations of perennial plants that allow them to be successful weeds of crop plants

Answer 23

Storage organs, vegetative reproduction, early growth, larger size

Question 24

Describe two differences between annual and perennial weeds

Answer 24

annual plants have a short life-cycle, complete within a year but perenial plants are plants that live for two years or more

Question 25

Describe how cultivation methods can be used to control the growth of weeds

Answer 25

Ploughing weeding crop rotation

Question 26

Describe the action of selective herbicides

Answer 26

selective herbicides have a greater effect on broad-leaved weeds

Question 27

Describe the action of systemic herbicides

Answer 27

Systematic herbicide spreads through vascular system of plant and prevents regrowth

Question 28

describe two environmental problems associated with applying insecticide to crops

Answer 28

toxicity to non-target species, persistence in the environment and biomagnification and biaccumulation in food chains, and production of resistant populations to pests

Question 29

explain the difference between a selective herbicide and a systematic herbicide

Answer 29

selective herbicides have a greater effect on broad-leaved weeds and systemic herbicides spread through the vascular system of the plant

Question 30

describe the use of disease forecasts in crop protection

Answer 30

application of fungicide based on disease forecasts are more effective than treating diseased crops

Question 31

explain why systematic herbicides are effective against weeds with the undergound storage organs

Answer 31

systematic herbicides spreads through the vascular system of the plant and reaches the underground storage organs and prevents regrowth

Question 32

Explain the meaning of the term "persistent pesticide"

Answer 32

chemicals that will not breakdown in the environment and bioaccumulation

Question 33

explain the difference between bioaccumulation and biomagnification

Answer 33

bioaccumulation is the build up of toxic chemicals in the body of an individual ingesting the chemical in its food, biomagnification is the overall effect of bioaccumulation along the food chain

Question 34

explain how application of a pesticide can produce a resistant population of a pest

Answer 34

pesticides acts as a selection pressure many individuals die any individual with the mutation which gives them resistance survive, they reproduce and pass their resistance an to offspring.

Question 35

Describe issues that arise when deciding on the level of animal welfare to provide on a pig farm

Answer 35

costs benefits improved quality ethical questions

Question 36

Describe the characteristics of a symbiotic relationship

Answer 36

co-evolved and intimate relationship between members of two different species

Question 37

explain the effect of a parasitic relationship on the host

Answer 37

parasites benefit in terms of energy or nutrients and the host is harmed by the loss of nutrients

Question 38

explain the benefit gained by some parasites in having an intermediate host as part of their life-cycle

Answer 38

allows them to complete their life-cycle and increases the probability of infecting their primary host

Question 39

explain why mutualism can be described as a type of symbiosis

Answer 39

it is an intimate and co-evolved relationship between two different species in which both species in the interaction benefit

Question 40

explain the benefit of co-operative hunting strategies

Answer 40

Co-opeerative hunting may benefit subordinate animals as well as dominant ones as they may gain more food than by foraging alone and less energy is used per individual and co-operative hunting enables larger prey to be caught and increases the chances of hunting success

Question 40

explain the benefits of a social system involving a dominance hierarchy

Answer 40

increases the chances of the dominant animals favourable genes being passed on to the offspring and animals often form alliances to increase their social status within the groups this lowers aggression which saves energy and provides experienced leadership.

Question 41

in honey bees, worker individuals are sterile but work to ensure that offspring of their relatives are fed. explain the altruistic behaviour of the worker bees

Answer 41

Worker bees feed the offspring of relatives because they have shared genes, and the feeding helps ensure that the offspring survive.

Question 42

on returning to their roost after feeding, vampire bats may regurgitate blood to feed an unrelated individual in the same social group. Explain the survival value which could be gained by feeding an unrelated individual.

Answer 42

there is an expectation that the other organism will act in a similar manner at a later time.

Question 43

describe the reproductive contribution made by queens, drones and workers in a honey bee colony

Answer 43

only the queens and drones are fertile and workers co-operative to raise the offspring of relatives.

Question 44

explain why long periods of parental care are needed for chimpanzees development

Answer 44

it allows the opportunity to learn complex social behaviours

Question 45

Explain the advantage to chimpanzees of complex social behaviours such as the use of facial expressions.

Answer 45

it helps support the social structure of the chimps.

Question 46

Describe the effect of the presence fo a dominant species on the species diversity of an ecosystem

Answer 46

it has lower species diversity because although the species richness may be high the relative abundance of some species is low

Question 47

Explain the negative impact on a species resulting from the loss of many individuals of a population

Answer 47

the species may lose some of its genetic diversity and this may limit its ability to adapt to changing conditions.

Question 48

Describe what is meant by the bottleneck effect

Answer 48

When small populations lose the genetic variations necessary to enable evolutionary responses to environmental changes

Question 49

Describe the effect of over-exploitation and later recovery on the genetic diversity of a species

Answer 49

small populations lose the genetic variation necessary to enable evolutionary responses to environmental change, following recovery the population has less genetic diversity than the original population due to inbreeding.

Question 50

Explain the possible impact of low genetic diversity in a small population

Answer 50

loss of the genetic variation necessary to enable evolutionary responses to environmental change and poor reproductive success.

Question 51

compare the species diversity in small isolated fragments compared with the larger ones.

Answer 51

less biodiversity in small fragments and less biodiversity in more isolated fragments

Question 52

habitat corridors can be created to remedy habitat fragmentation. Explain how a habitat corridor can increase biodiversity after local extinction.

Answer 52

Corridors allow movement of animals between fragments increasing access to food and choice of mate which lead to recolonisation of small fragments

Question 53

explain why the population of invasive species can become very large in their new habitats.

Answer 53

invasive species may well be free of the predators, parasites and pathogens and competitors that limit their population in their native habitat.