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SNAB edexcel A-level biology > Biodiversity and natural resources > Flashcards

Biodiversity and natural resources Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

The production of antifreeze proteins is an example of what type of adaptation?

A anatomical adaptation
B change in allele frequency
C physiological adaptation
D reproductive isolation

A

C

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2
Q

Anti-freeze glycoprotein (AFGP) is one type of anti-freeze protein.
Messenger RNA coding for AFGP is translated at a ribosome to produce a
polypeptide.
Describe how this polypeptide is then processed to make AFGP.

A
  • POlypeptide is then passed through the RER to golgi apparatus
  • carb added
  • modified in golgi
  • Packaged into vesicle for transport around the cell.
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3
Q

Some fish produce another anti-freeze protein, called AFP II.
The tissues of these fish were tested for the presence of AFP II and the mRNA
coding for AFP II.
The results are shown in the table.
Molecule Present in
AFP II protein: all tissues
AFP II mRNA: liver tissue only

Explain the distribution of the AFP II protein and AFP II mRNA.

A

mRNA is found in liver tissues only since gene is turned on or off only there.

so translation also only happens in liver cells.

from the liver, protein is transported around the body from the liver

so prevents freezing in all parts of the body.

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4
Q

Many different types of anti-freeze protein are produced by ray-fin fishes.
Analyse the data to explain when these ray-fin fish are likely to have evolved
the ability to produce anti-freeze proteins.

(population of these fish has increased over time through ice age periods and they existed from 75-252 million years ago) Karoo and quaternary periods

A
  • ice is a selection pressure for antifreeze proteins
  • so frequency of the anti-freeze proteins could’ve increased over time
  • ray fish only existent in quaternary and Karoo periods
  • so ray fish have likely evolved for producing the AFP during the karoo and Quaternary periods.
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5
Q

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

A
  • could increase genetic diversity
  • because new alleles introduced to the gene pool
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6
Q

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

A
  • sequences of DNA or bases can be compared
  • the more bases in common order, the more closely related the species is.
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7
Q

Describe how scientists could have determined that P. falciparum is a eukaryotic
organism and not a prokaryotic organism.

A
  • membrane bound organelles present
  • no plasmids present
  • RER present
  • ribosomes are larger
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8
Q

People with a heterozygous genotype for this condition do not develop severe
sickle cell anaemia.
The Yoruba are a group of people who live in West Africa.
In a population of 600 Yoruba individuals, 24 were found to have severe sickle cell
anaemia.
Calculate the number of heterozygous individuals in this population.
Use the Hardy Weinberg equation, p2
+ 2pq + q2
= 1.

A

we know that rr will be the ‘severe’ group, so 24/600= p^2 so p= 0.2

so consequently, q= 0.8

2 x 0.2 x 0.8 = 0.32

0.32 x 600= 192 heterozygous.

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9
Q

Individuals who are heterozygous for this condition are resistant to a severe
form of malaria, called cerebral malaria, that affects the brain. Individuals who
are homozygous for the sickle cell allele are more likely to develop severe
sickle cell anaemia.
The maps show the percentage of the population with the allele for sickle cell
anaemia and the distribution of P. falciparum in Africa. The location of the
Yoruba people is indicated with a cross (×).
per cent of
population
with the
sickle cell allele
(Haemoglobin S)

Analyse the data to explain how malaria has affected the percentage of individuals in
the Yoruba population with the allele for sickle cell anaemia.
(6)
.

A
  • as shown on the map, the highest concentration of the endemic is found in the north. This is also where malaria is found and where the Yoruba people live.
  • highest proportion of people with the sickle cell allele is found where there is malaria.
  • sickle cell anemia is most common where malaria is found.
  • malaria could have acted as selection pressure
  • so individuals heterozygous more likely to survive the disease and pass on their alleles to offspring
  • Over time, the frequency of the sickle cell allele increases in the population.
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10
Q

Saiga antelopes are related to a wide range of other species of antelope.
The diagram shows the phylogenetic relationships between some antelopes.
This diagram was produced using data from analysis of a protein.

(i) Explain how this diagram indicates that saiga antelopes are more closely related
to Antilope than to Antidorcas.

A
  • Andorcas are the most recent common ancestor of the saiga antelope.
  • so there are more similarities in the protein.
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11
Q

It is believed that C. hoffmanni and C. didactylus shared a common ancestor
before becoming isolated on either side of the Andes mountain range.
(i) Explain why they are now classed as different species.

A
  • they can no longer breed together to produce viable offspring
  • since they have been reproductively isolated.
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12
Q

) The map shows the distribution of two species of sloth.
There are currently two major populations of C. hoffmanni in South America.
B. pygmaeus is restricted to an island off the coast of Central America.
Each population occupies different habitats.
Discuss why the number of sloth species may change in the future.

A

increase due to:

Fragmentation of habitat / geographical isolation

Different selection pressures on populations of C. hoffmanni

Different allele frequencies within separate populations

Evolution leading to formation of new species

may decrease due to:

B. pygmaeus is currently critically endangered

At risk of natural disaster, disease, predation etc

  • Therefore may become extinct
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13
Q

(b) The population of red squirrels on Brownsea Island is one of several protected
populations in the UK.
(i) These red squirrels are not classed as endemic to Brownsea Island because they
(1)
A are also found in other locations
B are not at risk of extinction
C are not in competition with grey squirrels
D have a large population size

A

A

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14
Q

Scientists measure biodiversity using both species richness and the
heterozygosity index.
State what is meant by the following terms:
(2)
species richness
heterozygotic index

A
  • species richness: the number of species living in an area
  • proportions of heterozygous individuals in a population

-

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15
Q

Muscular dystrophy is a group of disorders that gradually cause muscles to weaken.
One type of muscular dystrophy, caused by a recessive allele, affects 10 people in
100 000 of the population.
(a) Calculate the number of carriers in a population of 17.02 million.
Use the Hardy-Weinberg equation, p2
+ 2pq + q2
= 1
(3)

A

dd= 0.0001 so
q= 0.01
p= 0.99

2 x 0.01 x 0.99= 0.0198

0.0198 x 17.02 million

= 336 996 carriers

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16
Q

Explain why the genotype frequency for males with DMD cannot be
calculated using this Hardy-Weinberg equation.

A
  • the value for 2pq cannot be calculated
  • because males can’t be carriers or heterozygous for the disorder
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17
Q

Why do plants need water

A
  • keep turgor pressure
  • keeps plants cool
  • photosynthesis
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18
Q

Explain how water moves through into the roots.

A
  • water enters root hair cells through osmosis down the water potential gradient.
  • so solute concentration is higher inside the root hair cell low water potential due to active transport of mineral ions.
  • moves further down the water potential gradient through cells and finally drawn into the xylem due to transpiration stream- water is continuously lost through stomata, and this echos further down as well.
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19
Q

Explain capillary action.

A
  • Since water is polar
  • Molecules are attracted to each other, so as some leaves a plant by transpiration, others are pulled behind them.
  • so water in the xylem goes under tension due to the transpiration stream
  • lignin prevents it from bursting under pressure
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20
Q

Explain how molecular phylogeny can be used to show that 2 populations are reproductively isolated. (3)

A
  • sequence of amino acids compared
  • for similarities and differences between order.
  • the larger the difference in sequence, the more likely they are to be reproductively isolated.
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21
Q

Describe how mutations can cause badgers on the east side of Bosphorus Strait can cause them to become 2 different species (4)

A
  • mutations may cause rise of a new allele
  • selection pressure may cause the allele to become advantageous
  • individuals with the allele more likely to survive and reproduce
  • populations then might become very different and can no longer breed to produce fertile offspring.
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22
Q

Define species richness

A
  • the number of species in an area
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23
Q

Define heterozygosity index

A
  • the proportion of individuals heterozygous for a particular trait.
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24
Q

In the human population, the frequency of an allele may change from one gen to the next. Explain why.

A
  • mutation may occur
  • causing the allele to become advantageous.
  • so may increase allele frequency due to natural selection
  • but may decrease due to people with the condition choosing not to have children.
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25
Q

How does the Hardy-Weinberg equation show evolution?

A
  • can show allele frequency change over time
  • if allele frequency stays the same, then no evolution has occurred
26
Q

In what one circumstance is the hardy Weinburg equation valid?

A
  • random mating
27
Q

Describe the differences between species richness and genetic diversity

A
  • species richness is number of species in an area, but genetic diversity is the number of alleles in a certain speices.
28
Q

What is the function of the middle lamella? Where is it found in a plant cell wall?

A
  • Provides stability to the plant.
  • forms the outermost layer of the cell wall, and acts as glue to stick adjacent plant cells together.
29
Q

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

A
  • formed from many layers of thylakoid membrane to increase SA for photosynthesis
  • thylakoid membranes contain chlorophyll to absorb light
  • electron carrier molecules in thylakoid membrane involved in ATP production.
30
Q

Describe how nitrate ions are transported from roots to leaves

A
  • through the xylem
  • dissolved in water
31
Q

Name the monomer that makes up cellulose

A

beta glucose

32
Q

compare and contrast the structure of a chitin molecule with cellulose (3)

A
  • both have glycosidic bonds
  • Every other glucose molecule is inverted
  • Chitin contains nitrogen, but cellulose doesn’t
33
Q

compare and contrast the structure of cellulose and amylopectin

A
  • cellulose is unbranched, but amylopectin is branched
  • cellulose is made of beta glucose, but amylopectin is made of alpha glucose
  • both contain 1,4 glycosidic bonds
34
Q

Devise a valid investigation to determine the effect of storage temperature on the tensile
strength of manila rope and nylon rope.

A
  • take ropes of the same length
  • stored for the same amount of time
  • clamp ropes and hang increasing newtons of weight until they snap
  • calculate change in tensile strength
35
Q

Describe how the tensile strength of these fibres could have been measured.

A
  • add increasing weights until ropes snap
  • keeping length of ropes the same
  • calculate tensile strength by dividing force/cross sectional area.
36
Q

Explain why the seedling needs a supply of magnesium ions.

A
  • to make chlorophyll
  • which is required for photosynthesis
37
Q

A range of minerals is necessary for the formation of healthy plant tissue.
Seedlings of rice plants were grown for two weeks in a complete solution containing all the
mineral ions required.
After two weeks, the plants were divided into three groups, A, B and C.
* The plants in Group A were grown in a complete solution.
* The plants in Group B were grown in a complete solution lacking magnesium ions.
* The plants in Group C were grown in a complete solution lacking calcium ions.
The plants were then grown for nine days. The diagrams show the plants at the end of the
growing time.
The labels L3 to L6 on the diagrams refer to the leaves in order of growth.
L6 was the last leaf to grow.
At the end of the growing time, L5 was dead and L6 was yellow in the plants in Group B.
Comment on the effects of deficiencies in magnesium ions and calcium ions on the growth of
these rice plants.
(4)

A
  • first leaf to die is leaf 5 in group B
  • but plants continue to grow in solution lacking Mg
  • but stop growing in solution lacking calcium
  • effect of Mg deficiency is shown earlier than the effect of calcium deficiency
38
Q

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

A
  • use plants of the same variety
  • use at least 5 different concs of nitrate solution
  • grow them for a set period of time
  • while keeping light the same with a lamp
  • measure the lengths of each plant after the period of growth to measure rate of growth.
39
Q

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

A
  • produced between new cells
  • because the middle lamella holds cell walls together.
40
Q

Function of plasmodesmata

A
  • cytoplasmic connection between cells
  • to allow for exchange of materials between cells.
41
Q

The concentration of magnesium ions in the soil was found to be very low.
Explain the effects of a shortage of magnesium ions on a plant.

A
  • cannot make chlorophyll
  • so less glucose produced due to less photosynthesis
  • so leaves may be stunted and yellow in appearance
42
Q

Give two reasons why a sieve tube element does not require rough endoplasmic reticulum
and ribosomes.

A
  • no ribosomes because no transcription
  • no protein synthesis, so no need for RER.
43
Q

Describe the structure of starch.

A
  • contains amylose and amylopectin
  • polysaccharide made of alpha glucose
  • contains 1,4 glycosidic bonds in between monomers
  • 1,6 glycosidic bonds between straight chains
44
Q

The electron micrograph shows a difference in the number of mitochondria in the sieve
tube element and in the companion cell.
Explain the difference in the number of mitochondria.

A
  • companion cells contain much more mitochondria
  • Sieve tube can’t carry out aerobic respiration
  • so the companion cells supply the sieve tube cells with ATP.
45
Q

State what is meant by the term tensile strength.

A

the force a fiber can withstand before breaking.

46
Q

In the 18th century, William Withering trialled the use of an extract of foxglove plants to treat a
heart condition.
Give four reasons why a contemporary drug testing protocol is an improvement on the trial used
by William Withering.

A
  • regulated by authorities
  • tested on tissues and animals before tested on humans
  • modern testing might involve double blind trials
  • placebo used as a comparison
47
Q

Explain why healthy volunteers were given different doses of the drug or a placebo

A
  • to check for side effects
  • to make sure side effects are from drug and not placebo
48
Q

compare and contrast this drug testing protocol with that used by William Withering he tested digitalis soup

A
  • placebo used by trial but not by William
  • both used different doses to determine safe dose.
  • William did not use healthy volunteers.
49
Q

explain how seed are chosen for seed banks (3)

A
  • from different plants
  • to maintain genetic diversity
  • then x-rayed to check for viability
50
Q

what are the conditions that seeds are stored in seed banks? Why? (3)

A
  • cool and dry
  • to prevent germination
  • and to prevent enzyme activity
51
Q

where is calcium pectate found?

A
  • middle lamella
52
Q

Describe the functions of xylem

A
  • to transport water and mineral ions around the plant
  • provide structural support to the plant
53
Q

Describe the structure of a cellulose microfibril (4)

A
  • polymer of beta glucose
  • monomer units held together by 1, 4 glycosidic bonds
  • microfibrils held together by hydrogen bonds
  • unbranched chains
54
Q

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

A
  • less chlorophyll so less photosynthesis
  • so less glucose produced
  • so less amino acids produced- giving the plant stunted growth and the leaves a yellowish appearance.
55
Q

Explain why starch must be broken down before it can be used by the cells of the gro
plant

A
  • because it’s broken down into glucose
  • which is soluble and can be used in respiration.
56
Q

describe and explain how the xylem is adapted for it’s role for strength to the plant and transporting water (4)

A
  • reinforced by lignin
  • which provides strength and stability to the plant
  • for transporting water, it is hollow
  • which allows for vertical movement of water.
57
Q

In Kenya, an in-situ conservation project has been set up to make paper from elephant dung.
This project aims to help conserve elephant populations, conserve biodiversity and help local
communities.
Elephant conservation often involves the setting up of protected areas to stop poaching.
Local people are banned from entering these areas.
This method of elephant conservation sometimes causes conflict with local people, as
elephants can trample and eat crops in nearby farmland. Farmers sometimes burn areas of
grassland and forest to stop elephants destroying their farmland.
The new paper conservation project encourages local people to make paper from elephant
dung they collect from the conservation area. The paper they make is sold at a high price.
Conservationists measured the effect of the new paper project on the index of diversity of
the area over two years. They also measured the effect of a protected conservation area
where local people were banned from entering on the index of diversity. The results are
shown in the table.

Give two advantages of in-situ conservation of elephants compared with ex-situ
conservation of elephants.

A
  • in situ means animal behaviour is unchanged, natural behaviours are kept
  • less inbreeding
58
Q

Explain the effect of the new paper project on biodiversity compared with the protected
area where local people were banned.

A
  • new paper seems to have increased biodiversity
  • because less grassland is burned and less elephants are poached.
  • ## where local people were banned, it has shown a decrease in biodiversity
59
Q

In Kenya, an in-situ conservation project has been set up to make paper from elephant dung.
This project aims to help conserve elephant populations, conserve biodiversity and help local
communities.
Describe the limitations of CITES in the conservation of organisms such as elephants.

A
  • not every country may sign the treaty
  • expensive to constantly monitor species.
60
Q

Organic farming does not use artificial insecticides, herbicides or fertilisers, all of which are
used in conventional farming.
Students investigated the effect of organic farming on the species diversity of butterflies.
They compared fields used for growing crops on an organic farm and on a conventional
farm.
Some conventional farms have converted to organic farming.
A further experiment was carried out to investigate the effect on species diversity of how
long the farms have used organic methods.
(i) Butterflies and plant species were sampled from a range of farms that had used organic
farming methods for different lengths of time.
The number of plant species and the number of butterfly species were recorded.
The results are shown in the table.

Explain how the number of years of organic farming affects the biodiversity of butterfly
species.

(3)

A
  • butterfly species increases
  • because more plant species available
  • to act as more food sources.
61
Q

The Northern elephant seal is a mammal found in the Eastern Pacific Ocean.

In the nineteenth century, Northern elephant seals were hunted and this reduced the
population to about 20 seals.
The seals were listed as an Appendix II species when CITES was established in the 1970s.
The population has now recovered to over 100 000 individuals.
The seals in this population have developed health problems, including a high mortality rate
for newborn pups, deformities and weak immune systems.
(i) Describe the role of treaties such as CITES in maintaining global biodiversity.

A
  • to prevent poaching
  • by having countries sign treaties
62
Q

The World Wide Fund For Nature (WWF) is the largest conservation organisation in the
world.
The WWF recently claimed that ‘some 46 000 to 58 000 square miles of forest are lost each
year. This is equivalent to 36 football fields every minute’.
This level of deforestation affects biodiversity.
Scientists studied the relationship between protecting land from deforestation and the
percentage of species conserved.
The graph shows the results of the study.

Analyse the data in the graph to explain how protection of land affects the percentage of
species conserved.

(4)

A
  • there is a positive correlation between land conserved and species conserved.
  • because the land may provide species with niches or habitats
  • but even with 0 land, 10% of species still survive
  • possibly because they live in soil or other non-tree habitats.

SNAB edexcel A-level biology (8 decks)

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