Topic 4 exam questions Flashcards
get dat A innit bruvs
State what is meant by the following terms (2)
Species richness
Heterozygosity index
-Species richness measures number of species in a habitat
-Hetrozygosity index is a measure of genetic diversity within a species
State what is meant by biodiversity (2)
Measure of the variety of living organisms of different species in a habitat
Compare species diversity with species richness (2)
-Both measure the number of different species in a community
-Species diversity takes into account the abundance of species but species richness does not
Explain the advantages of drying seeds before storage (2)
-Extends storage time of seeds
-Drying prevents germination of seeds
Explain the benefits of seed conservation (2)
-Prevents species from becoming extinct
-Conserves genetic diversity
State suitable conditions for keeping seeds in a bank (2)
-Cold
-Dry
Explain why starch must be broken down before it can be used by the cells of the dying plant (2)
-To produce glucose
-Which is used in respiration
Justify the continued funding of SSGV seed bank (3)
-SSGV conserved genetic diversity
-Crop varieties kept in SSGV are protected from natural disasters
-Crop varieties in SSGV may have traits that are useful in the future e.g. drought resistance
-SSGV helps ensure future of food security
Describe how seeds are preserved for long periods of time in a seed bank (3)
-Seeds are cleaned
-Seeds are dried
-Seeds are stored at cold temperatures
Seed banks obtain seeds collected from a number of plants of each species
Explain the advantages of this for the conservation of a plant species (2)
-Ensures genetic diversity
-Therefore greater chance of survival
-If the plants are reintroduced conditions may have changed
Describe the role that zoos play in animal conservation (3)
-Protection from poachers and hunters
-Education via conservation
-Repopulation via breeding programmes
-Research, improving health and discovering better nutrition
Explain why captive breeding programmes are important for maintaining biodiversity (3)
-Increases population size of species
-Increases genetic diversity
-Therefore prevents extinction of species
When these two cubs become adults, they were separated and sent to zoos in Poland and Italy
Explain why these offspring were not allowed to remain in the same zoo (3)
-To prevent related animals from breeding with each other
-To prevent inbreeding depression
-To increase genetic variation within the species
The Scottish wildcat can interbreed successfully with domestic cats
Explain the effect this could have on the genetic diversity of the Scottish wildcat (2)
-Increases genetic diversity
-Because of reintroduction of new alleles to the population
Captive breeding programmes can be used to increase the number of flamingos
Flamingos kept in zoos are given food containing carotene pigments to make their feathers stay pink
Discuss the factors that need to be taken into account when zoos carry out captive breeding and reintroduction programmes for the greater flamingo (4)
-Maintenance of genetic diversity
-By selection of mates/use of stud books
-Stud books prevent inbreeding depression
-Habitat protected from development
Sympatric speciation can occur when behavioural barriers result in the reproductive isolation of populations
Suggest one behavioural barrier and explain how it may result in reproductive isolation (2)
-Different mating rituals
-No longer attracting the opposite sex for mating
A new species of mosquito has evolved in the tunnels of the London underground. These mosquitoes are believed to be he descendants of bird-biting mosquitoes which colonised the tunnels 100 years ago.These mosquitos now feed on rats, mice and human beings instead of birds
Explain how this species of mosquito may have evolved (5)
-Mosquitoes are geographically isolated in the tunnels
-Random genetic mutations cause variation in the population which allows some individuals to feed on rats, mice and humans
-These individuals are more likely to survive and reproduce
-The proportion of individuals in the population with this mutation will change overtime
-Over many generations these populations become genetically distinct from the above ground population
Before the 1960s, all of the hedgehogs on an island were dark coloured
It has been suggested that the blonde hedgehogs are less likely to be killed by cars at night
Explain the role of natural selection in the increase in the number of blonde hedgehogs on this island of alderney (3)
-Selection pressures from environment make it less likely the hedgehogs survive
-Hedgehogs with lighter coats/advantageous characteristics survive and reproduce
-Passing on advantageous allele
-Alleles for advantageous characteristic become more common in the population over time
Eukarya is one of the three domains
Name the other two domains (2)
- Archaea
- Bacteria
Scientists classify organisms into taxonomic groups, such as the three domains
Explain how organisms can be classified into taxonomic groups (2)
-Individuals with shared characteristics are placed in a group
-Groups are based on observable characteristics, behavioural similarities, similarities in DNA
When Carl Woese first suggested that all organisms could be classified into one of the three domains, his ideas were not accepted
Suggest how Woese’s idea was critically evaluated (3)
-Scientific findings published in a journal
-Presented at a scientific conference
-Peer review
Woese suggested that organisms could be placed in taxonomic groups based on molecular phylogeny. Explain what is meany by this statement. (4)
-Organisms with common features are placed in a group
-Taxonomic groups have specific differences
-Phylogeny is the genetic relationship between organisms
-Molecular phylogeny is based on similarities in DNA sequence
Describe how the scientific community would have evaluated Woese’s theory (2)
-Through peer review
-Repeating experiment to confirm or validate findings
Features of Bacteria
Features of Eukaryota
Bacteria:
Ribosomes
Cell membrane
Slime capsule
Eukaryota:
Ribosomes
Smooth endoplasmic reticulum
Cell membrane
Scientists tested the RNA of these microorganisms and discovered that they belonged to the domain archaea
Explain how molecular phylogeny could be useful to identify the microorganisms as Archaea and not Bacteria (2)
-Molecular phylogeny compares RNA/DNA
-Compares sequences of amino acids, to determine if sequence is more similar to Archaea than Bacteria
Give reasons why the use of fibres from plants in sustainable (2)
-More plants can be regrown
-Plants are a renewable resource
Explain why the use of bamboo fibres to make coffee cups is sustainable (2)
-Available to future generations
-Bamboo is a renewable resource
-More bamboo plants can be grown
Fibres can be extracted from the stems of nettle plants and used to make clothing
Explain why the production of fibres from nettles is more sustainable than fibres produced from crude oil (3)
-Nettle plants can be grown so they are renewable
-Crude oil is a non-renewable resource and will run out
-Use of fibres from nettles will be available to future generations
In modern drug testing protocols, the first stage that patients with an illness are involved is
A) Preclinical trials
B) Phase 1
C) Phase 2
D) Phase 3
C - Phase 2
In modern drug testing protocols, side effects such as nausea will first be identified in healthy volunteers during
A) Preclinical trials
B) Phase 1
C) Phase 2
D) Phase 3
B - Phase 1
Modern drug testing protocols must ensure that new drugs are effective at treating patients
Explain the role that a placebo and a double blind trial have in producing valid conclusions (4)
Placebo:
-It provides a control group for comparison
-Therefore ensuring that the drug is causing the effect
Double blind trial:
-Neither doctors nor patients know who has been given the actual drug treatment
-Therefore ensures that bias is removed from the trial
Explain why healthy volunteers were given different doses of the drug or placebo (2)
-Checking for side effects
-Different doses to determine safe dose
-Placebo to make sure that any side effects described were due to the drug
Give four reasons why a contemporary drug testing protocol is an improvement in the trial used by William Withering (4)
Safer:
- Because pure drug used rather than extract
-Due to pre-testing on cells/animals before testing on humans
-Regulated by legislation
Reliability:
-More people are tested
Validity:
-Placebo is used as a comparison
-Modern testing may involve double-blind trials
Describe how clinical trials of a vaccine would be conducted (3)
-Small groups of healthy volunteers are given the vaccine to test for side effects
-Healthy volunteers tested for presence of antibodies to the virus
-A group of people at risk of contracting the disease are given the vaccine
-Number of people who develop the viral disease are monitored
A vaccine was given to health workers and immediately family of those with Ebola
Justify the use of this vaccine, even though the clinical trials had not been completed (4)
-Large numbers of people died from the disease
-Health workers are in close contact with people suffering from the disease
-The side effects of the vaccine will not be worse than contracting Ebola
-Vaccinating immediate family will help reduce the spread of the disease
-If health workers are vaccinated they could care for more people
Describe how a safe dose of a cancer drug could be determined (3)
-Test the drug on healthy individuals
-Then test on group of individuals with cancer
-Gradually increasing the dose to determine dose that does not cause side effects
A three-phase protocol will be used when developing the phospholipase inhibitor as a new drug
Explain the purpose of each phase of this protocol for a phospholipase inhibitor (3)
Phase 1: To make sure inhibitor is not harmful
Phase 2: To see if it is effective in treating the condition
Phase 3: To gather data for statistical tests/look for side effects
In an investigation testing the effectiveness of a painkiller produced from conotoxin, the new pain killer was tested on a group of healthy volunteers
Explain the reasons for this stage in the testing of the painkiller (2)
- To determine safe dose
-To determine side effects
Explain the preclinical trials that will be carried out then testing a new drug (2)
-Tested on animals/tissue samples
-To determine safe dosage
Explain what is meant by the term double-blind trial (2)
-A trial using a placebo
-Where the patients and the doctors do not know who has been given the drug and who has not, to prevent bias
Describe how aseptic techniques are used when handling bacterial cultures (3)
- Sterilising work surfaces
-Sterilising equipment with heat
-Limiting the time the containers are open
-Working near a bunsen burner to provide a convection current
Describe 2 aseptic techniques that should be used when working safely with bacteria (2)
- Flaming the instruments
-Keeping lids off for minimal time
Explain why some bacteria can grow rapidly in skin wounds (3)
-The temperature is warm, increasing the rate of reactions in bacteria
-Availability of energy source from blood
-Oxygen availability is good, allowing aerobic respiration
Explain the relationship between the structure and functions of a granum in photosynthesis (3)
Granum is formed from many layers of thylakoid membranes to increase surface area for absorbing light, thylakoid membranes contain chlorophyll to absorb light, and electron carrier molecules in thylakoid membranes involved in ATP production
Describe the structures in the chloroplasts that are involved in the light-dependent reactions of photosynthesis (3)
-Thylakoids
-Made of membranes
-Arranged as stacks
-Contain pigment chlorophyll
-Arranged as photosystems
Describe how the membranes inside the chloroplast are involved in photosynthesis (3)
-Site of light-dependent reaction
-Contain chlorophyll, photosystems, electron carrier proteins
-ATP is in the thylakoid membrane
-Thylakoid membranes provide space for accumulation of H+ ions
Describe the structure of chloroplasts in relation to their roles in photosynthesis (3)
-Compartmentalisation
-Thylakoid membranes are the sight of light-dependent reactions
-Contain chlorophyll, photosystems, electron carrier proteins
-Stroma is the sight of light-independent reaction where RUBISCO carbon fixates CO2 and RuBP
Phosphate ions are required for the synthesis of
A) Cellulose
B) Chlorophyll
C) Nucleic acids
D) Sucrose
Nucleic acids
Nitrate ions are required for the synthesis of
A) Amino acids
B) Cellulose
C) Starch
D) Sucrose
Amino acids
Describe the importance of magnesium ions in the production of plant fibres (2)
-Magnesium is essential to produce chlorophyll
-Chlorophyll is necessary to produce glucose during photosynthesis
-Glucose needed to produce cellulose for the cell walls
Devise an investigation to determine the effect of nitrate ions on the concentration of a plant (5)
-Use plants that are the same age and place them all in separate soil in different containers
-Use a range of at least five different nitrate concentrations
-Control temperature by keeping the plants all in the same room and exposing them all to the same amount of light
-Grow all of them for 2 weeks
-Come back and measure the height of each plant in each concentration
-Deduce which concentration has the greatest growth on the plant
-Repeat the experiment with the same nitrate concentrations to calculate a mean value
Describe the effects of a shortage of magnesium ions on a plant (3)
-Shortage of magnesium ions limits the production of chlorophyll
-Lack of glucose due to less photosynthesis
-Therefore plant leaves may be yellow and the plant may be small
Describe the importance of nitrate ions to plants (3)
-Nitrates are used to make amino acids
-Growth is reduced if nitrates are lacking
-Nitrates needed to make DNA/RNA/nucleic acids/ATP
Name a plant tissue that has lignin in its cell walls
Xylem or Schelerenchyma
Tissues that contain lignin provide strength to plant fibres
Describe the position in the stem of those tissues that contain lignin (2)
Schelerencyma fibres on the outer side of the vascular bundle
Xylem vessels are inside the vascular bundle
A nucleus will be found in a
A) companion cell
B) sclerenchyma fibre
C) sieve tube
D) xylem vessel
A - Companion cell
Xylem and sclerenchyma fibres both
A) provide support
B) transport glucose
C) transport hormones
D) transport mineral ions
A - Provide support
The cell wall forms a greater percentage of the total mass of the sclerenchyma fibre than of a phloem sieve tube
Why is this the case?
Sclerenchyma fibres have thickened, lignified cell walls
Nitrate ions are required for the synthesis of…
Amino acids
Phosphate ions are required for the synthesis of…
Nucleic acids
Magnesium ions are present in the structure of…
Chlorophyll
Explain why a diet based on plant protein produces lower greenhouse gas emissions than a diet based on animal protein (3)
-Plants produce biomass from photosynthesis
-Plants remove CO2 from the atmosphere
-Because animals produce CO2 by respiration
-Some animals produce methane
Beef cattle are traditionally reared by grazing on natural pastures (grassland)
In recent years, large areas of rainforests have been cleared to produce beef
Explain why the farming of beef cattle on deforested land produces more greenhouse gas emissions than from those reared on natural pastures (3)
-Deforestation cuts down trees which are carbon sinks
-Burning/decomposition of these trees releases CO2 into the atmosphere
-Without trees there is less/no photosynthesis to remove CO2 from atmosphere
What is an endemic species? (1)
A species only found in one location
When a seed bank receives new seeds, it processes them in several ways.
The processes can include the following stages:
-Washing the seeds with disinfectant
-Allowing the seeds to dry
Explain the advantages of these two stages (3)
-Washing with disinfectant will kill any microorganisms
-Drying to reduce chance of germination / decrease enzyme action
-Therefore preventing decay / infection / damage to the seeds
Describe one advantage and one disadvantage of using ropes made from plant fibres rather than ropes made from oil-based plastics (2)
-Advantage – being sustainable / can decompose / is biodegradable
-Disadvantage – less strong / can decompose/ is biodegradable
Describe the positions in the stem of those tissues that contain lignin (2)
-Sclerenchyma (fibres) on the outer side of the vascular bundle / phloem
-Xylem vessels on the inner side / inside of the vascular bundle
Explain why the seedling needs a supply of magnesium ions (2)
-Magnesium is needed to make chlorophyll
-Because chlorophyll is required for photosynthesis
-Because shoots need (chlorophyll) to carry out photosynthesis to grow
Describe how forests can be managed as a sustainable resource (2)
-Replacing trees that have been cut down
-Remove / cut down older trees
-Replace with seedlings / young / rapidly growing trees
Give two biotic factors, other than cutting down trees, that could affect the number of bird species observed in a forest (2)
-Food availability
-Interspecific competition
-Predation
-Disease
Describe the difference between the terms niche and habitat (2)
-Niche is the role an organism plays in its habitat
-Habitat is the place where an organism lives
State what is meant by the term ecosystem (1)
-An area with organisms and non-living components / abiotic factors
Describe the role of mineral ions in the production if plant biomass (3)
-Nitrate ions needed for synthesis of DNA and nucleic acids
-Magnesium ions needed to make chlorophyll
-Calcium ions needed to make calcium pectate
-Phosphates are needed for membranes / ATP / NADP / nucleic acids
To conserve plant species , seeds may be stored in seed banks
Explain why cold and dry conditions are required for the storage of these seeds (3)
-Reduces / prevents enzyme activity / inhibits metabolic reactions
-Prevents germination
-Prevents bacteria growth / fungal growth / decomposition
Explain the effect of an increase in temperature on germination of the seeds (3)
-Increase in temperature increased germination
-Because there is more kinetic energy and more frequent collisions between substrate and enzyme
-Therefore starch is broken down / hydrolysed faster
-Greater supply of glucose increases rate of respiration
Explain why, In the wild, several species of deer can live in the same area (2)
-Each species occupies a different niche
-Therefore there is no competition between deer for resources
Devise a procedure that could be used to measure plant biodiversity in these two areas (4)
-Use random sampling technique in the two areas
-Use 1mx1m quadrats to sample at least 10 times in each area
-Count the number of species in each quadrat
-Count the number of individuals of each species in each quadrat
-Calculate diversity index / t-test
