Topic 4 Biodiversity and natural resources

Question 1

Describe an advantage and disadvantage of using ropes made from plant fibres instead of oil based plastics. (2)

Answer 1

-Plant fibres are sustainable/biodegradable/can decompose.
-However they are less stronge.

Question 2

Describe how scientists test if a drug is appropriate for humans after testing on animals. (4)

Answer 2

-First test the drug on healthy patients.
-Treat one group of patients with the drug and another group with existing treatment.
-Neither the doctors nor patients should know which treatment is being used.
-Participants must be monitored for side effects.
-Compare outcomes of patients treated with drug to control group.

Question 3

Explain how breeding programmes in zoos maintain genetic diversity of captive populations. (3)

Answer 3

-Animals are selected to prevent breeding with closely related individuals.
-Stud book is used to select individuals for mating/keep a record of all breeding events.
-Exchange of animals/gametes between zoos.

Question 4

During drug testing explain why healthy volunteers are given different doses of the drug or a placebo. (2)

Answer 4

-To check for side effects.
-Different doses to determine a safe dose.
-Placebo to make sure any side effects are due to drug only.

Question 5

Describe how aseptic techniques are used when handling bacteria cultures. (3)

Answer 5

-Flame instruments.
-Disinfect workbench before and after use.
-Keep lids off of containers for minimal time.
-Work near bunsen burner to create a convection current.

Question 6

State suitable conditions for keeping seeds in a seed bank. (2)

Answer 6

-Very cold temperature to be used (freezing).
-Very dry.

Question 7

Explain the role that a placebo has in drug testing. (2)

Answer 7

-Provides control group for comparison.
-Therefore ensuring the drug is causing the effect.

Question 8

Explain the role that a double blind trial has in drug testing. (2)

Answer 8

-Neither doctors nor patients know who has been given the actual drug.
-Therefore removes bias from trial.

Question 9

Devise a procedure that scientists may have used to measure the effects of plant extracts on pathogenic bacteria. (4)

Answer 9

-Use a minimum of 5 different agar plates which are inoculated with bacteria.
-Then add the different plant extracts into the agar plates with filter paper discs.
-Use the extracts separately and in combination.
-Incubate at 37 degrees for an appropriate time period.
-Then measure the zone of inhibition by finding the area then compare values. The larger the zone of inhibition the more effective the antimicrobial properties.

Question 10

Explain the advantages of drying seeds before storage. (2)

Answer 10

-Extends storage time.
-As drying prevents seeds from germination.

Question 11

Justify the benefits of conserving seeds. (3)

Answer 11

-Prevents seeds from going extinct.
-Conserves genetic diversity.
-Safeguarding of genes may prove to be useful in the future.
-Also allows for reintroduction of species in the future.

Question 12

Explain why bacteria are able to multiple in bloodstream when they enter body. (3)

Answer 12

-The temperature in the blood is warm which.
-The temperature is suitable for bacterial enzymes.
-Glucose used for respiration.
-Amino acids used for growth.

Question 13

Explain why use of bamboo fibres to make coffee cups is suitable. (2)

Answer 13

-Available to future generations
-As bamboo is a renewable resource.
-As it can be regrown.

Question 14

Describe the roles that zoos play in animal conservation. (3)

Answer 14

-Zoos protect animals from poachers/hunters.
-Zoos can increase population size of animal through breeding programmes.
-Zoos can improve health of animal and improve genetic database of animal.

Question 15

Explain the purpose of each phase of three phase drug test. (3)

Answer 15

-Phase 1: Done to find a safe dosage.
-Phase 2: Done to see if drug is effective in treating condition.
-Phase 3: Done to gather data to look for any rare side effects.

Question 16

Explain why seeds are sterilised and dried before being put into a seed bank. (3)

Answer 16

-Sterilising the seed will kill any microorganisms.
-Drying the seed reduces chance of germination.
-Therefore preventing infection to the seeds.

Question 17

Explain why production of fibres from nettles is more sustainable than producing fibres from crude oil to make clothing. (3)

Answer 17

-Nettles can be grown so they are renewable.
-Crude oil is non renewable and will run out.
-Use of fibres from nettles will be available to future generations.
-Clothing made from nettles is biodegradable.

Question 18

Describe how the safe dose of a cancer drug could be determined. (3)

Answer 18

-Test drug on healthy individuals/bacterial cultures.
-Then test drug on a group of individuals with cancer.
-Gradually increase dosage to determine dose that doesn’t cause side effects but is effective.

Question 19

Explain the relationship between the structure and functions of a granum in photosynthesis. (3)

Answer 19

-The granum contains many stacks of thylakoids which provides a large surface area to absorb light.
-Thylakoid membranes contain chlorophyll to absorb light.
-Electron carrier molecules in thylakoid membrane involved in ATP production.

Question 20

Describe how nitrate ions are transported from the root to the leaves. (2)

Answer 20

-Through xylem vessel.
-In water/via transpiration stream.

Question 21

How are monomers held together in a cellulose molecule. (1)

Answer 21

-By glycosidic bonds in an unbranched chain.

Question 22

Compare and contrast the structure of cellulose and amylopectin. (3)

Answer 22

-Both are polysaccharides of glucose.
-Both contain 1,4 glycosidic bonds.

-Cellulose contains Beta glucose whereas amylopectin contains Alpha glucose.
-Cellulose isn’t branched and doesn’t have 1,6 glycosidic bonds whereas amylopectin is branched and has 1,6 glycosidic bonds.

Question 23

State one difference between the hexose sugars in cellulose to hexose sugars in amylopectin. (1)

Answer 23

-Amylopectin has alpha glucose whereas cellulose has beta glucose.

Question 24

Name the bond between adjacent cellulose molecules in a cellulose microfibril. (1)

Answer 24

-Hydrogen bonds.

Question 25

Explain why a seed needs a supply of magnesium ions. (2)

Answer 25

-Magnesium is needed to make chlorophyll.
-Chlorophyll is required for photosynthesis.
-Shoots need chlorophyll to carry out photosynthesis to grow.

Question 26

Devise an investigation to determine the effect of nitrate ion concentration on the growth of young peanut plants. (5)

Answer 26

-Use plants that are of the same variety/age.
-Use a range of at least 5 different nitrate concentrations.
-Ensure to control temperature by placing test tubes in water bath.
-Grow for a set period of time.
-Measure growth by seeing how many flowers have appeared on each plant. (This is a measure of germination)
-Repeat experiment at each nitrate concertation to find mean values.

Question 27

What properties can lignin provide to cell walls in plants? (1)

Answer 27

-Strength and waterproofing.

Question 28

Name a plant tissue which has lignin in its cell walls. (1)

Answer 28

-Xylem.
-Sclerenchyma.

Question 29

Explain the role of the middle lamella when a plant cell completes mitosis. (2)

Answer 29

-Produced between adjacent new cells.
-As middle lamella holds cell walls together.

Question 30

Explain the function of the plasmodesmata. (2)

Answer 30

-Cytoplasmic connections between cells.
-Allows transport/communication between cells.

Question 31

Explain the effects of a shortage of magnesium ions on a plant. (3)

Answer 31

-Limits production of chlorophyll.
-Lack of glucose due to less photosynthesis.
-Therefore plant will grow less so it will be smaller and the leaves will be yellow.

Question 32

Give two reasons why a sieve tube element does not require RER and ribosomes. (2)

Answer 32

-There will be no transcription meaning ribosomes not needed for translation.
-No proteins will be synthesised to be processed by RER.

Question 33

Explain the difference in the number of mitochondria between a sieve tube element to a companion cell. (3)

Answer 33

-Companion cell has more mitochondria than the sieve tube.
-The role of the sieve tube is to provide a channel so cellular contents are kept to a minimum.
-The sieve tube has no ability to carry out aerobic respiration
-ATP is supplied to the sieve tube by the companion cell.

Question 34

What is meant by tensile strength? (1)

Answer 34

-The force the fibre can withstand before breaking.

Question 35

Explain how the structure and properties of starch are related to its function as a storage molecule. (3)

Answer 35

-Contains glucose which is needed for respiration.
-Insoluble so it has no osmotic effect.
-Amylose is coiled making starch compact meaning more alpha glucose can be stored.
-Amylopectin is branched meaning it can be rapidly hydrolysed.

Question 36

Describe the positions in the stem of those tissues that contain lignin. (2)

Answer 36

-Sclerenchyma, on outer side of vascular bundle.
-Xylem, on inner side of vascular bundle.

Question 37

Describe the importance of magnesium ions in the production of plant fibres. (2)

Answer 37

-Magnesium is needed to produce chlorophyll.
-Chlorophyll is needed to produce glucose in respiration.
-Glucose is needed to produce cellulose for cell walls.

Question 38

Devise a method to find the relationship between the actual diameter and the tensile strength of kapok fibres. (6)

Answer 38

-Extraction of individual fibres from plant.
-Callipers used to measure diameter of fibres.
-Ensure to keep length of fibre same.
-Clamp fibres and hang mass from fibres.
-Add masses at regular intervals until the fibre breaks.
-Repeat to find a mean at each diameter.
-Divide force by cross sectional area.

Question 39

What is meant by the term endemic? (1)

Answer 39

-Found only in one geographical location.

Question 40

The Scottish wildcat can interbreed successfully with domestic cats.
Explain the effect this could have on the genetic diversity of the Scottish wildcat. (2)

Answer 40

-Increases genetic diversity.
-As there is an introduction of new/different alleles into the population.

Question 41

Describe what needs to be measured in order to compare the biodiversity of two rainforests. (2)

Answer 41

-The number of different species.
-The number of individuals per species.

Question 42

Give an example of how sloths have behavioural, physiological and anatomical adaptations to their environments. (3)

Answer 42

-Behavioural: They sleep for long periods of time/move slowly.
-Physiological: Slow metabolism.
-Anatomical: Have hooked claws.

Question 43

Explain how the primary structure of trypsin molecules can be used to produce a phylogenetic tree. (3)

Answer 43

-Determine the sequence of amino acids for trypsin.
-Determine the number of differences in sequences of amino acids between species.
-The greater the number of differences the less closely related species are.

Question 44

Explain how two species of snake could have arisen from a common ancestor. (4)

Answer 44

-Mutation leads to variation within population of grass snakes.
-Natural selection led to those snakes which were better camouflaged to survive and reproduce.
-Creating offspring which are part of 2 different populations with differing allele frequency.
-As a result of natural selection, 2 populations became reproductively isolated.
-Sympatric speciation in context of new species developing in same habitat.

Question 45

Explain why 2 types of sloths are classified as different species. (2)

Answer 45

-They are no longer able to interbreed to produce fertile offspring.
-As the populations have become reproductively isolated.

Question 46

What does the term niche mean? (1)

Answer 46

-The role a species has in its community/environment.

Question 47

During the civil war in Mozambique, from 1977 to 1992, 90% of the African elephants were killed for the ivory in their tusks.

In most African elephant populations, 2% to 4% of elephants do not grow tusks.

Explain why the percentage of elephants without tusks in Mozambique will probably increase in the future. (4)

Answer 47

-Many of the elephants with tusks were killed for their ivory.
-Elephants without tusks are more likely to survive and breed.
-Therefore passing on alleles for no tusks to offspring.
-Increasing frequency of homozygous recessives in the population.

Question 48

Describe how the Hardy-Weinberg equation can be used to provide evidence for changes in populations. (2)

Answer 48

-Calculate the allele frequency/number of dominant and recessive alleles in population.
-Regular sampling over time.

Question 49

Describe how mutations can lead to a different species to form in a population. (4)

Answer 49

-Mutations results in the production of new alleles.
-Selection pressures cause alleles/mutations to be advantageous.
-More individuals with advantageous alleles survive and reproduce.
-After time, the two species within the population wouldn’t be able to reproduce with each other to produce fertile offspring.

Question 50

What is meant by species richness? (1)

Answer 50

-Measures the number of species in a habitat.

Question 51

What is meant by heterozygosity index? (1)

Answer 51

-Measure of genetic diversity within a species/population.

Question 52

What is meant by the term species? (1)

Answer 52

-Group of organisms that can interbreed to produce fertile offspring.

Question 53

Explain why the frequency of an allele in a human may change from one generation to the next. (3)

Answer 53

-Allele may undergo a mutation.
-As gene flow may cause alleles to be lost or gained from the population.
-Due to natural selection/selection pressure.
-People with this allele may not have children

Question 54

Explain how the Hardy-Weinberg equation can be used to show that natural selection is occurring in a population. (2)

Answer 54

-Hardy-Weinberg equation shows allele frequency in a population.
-If natural selection occurs there would be a change in allele frequency overtime.

Question 55

Explain how molecular phylogeny could be used to determine the relationships between the Scottish wildcat and other subspecies of European wildcat. (2)

Answer 55

-Compare sequences of bases in DNA/amino acids in proteins.
-More similarities in common, the more closely-related the sub species.