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A-Level Biology Edexcel A > Biodiversity and Natural Resources > Flashcards

Biodiversity and Natural Resources Flashcards

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1
Q

Define biodiversity

A

The variety of living organisms in an area

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2
Q

What are the two ways of measuring biodiversity?

A

1) Species richness - Number of species in a habitat

2) Genetic diversity - Measure of genetic variation in a species, or the number of alleles in a gene pool

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3
Q

How do you calculate the heterozygosity index?

A

Number of heterozygotes/total individuals in population

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4
Q

What is the formula for biodiversity index?

A 
D = [N(N-1)]/∑n(n-1)
D = diversity index
N = total number of organisms
n = total number of organisms of each species
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5
Q

Define endemic

A

When a species is unique to a particular geographic location

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6
Q

Define niche

A

The role of a species in a community, and its interaction with biotic and abiotic factors

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7
Q

What are the 3 types of adaptations?

A

Anatomical adaptations: Structural adaptations (external or internal), e.g. thinner beak of finch to hunt for insects
Behavioral adaptations: Changes in behavior that improve the organisms’s chance of survival, e.g. mating calls
Physiological adaptations: Internal processes that increase chance of survival, e.g. blood flow regulation through skin

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8
Q

Explain natural selection

A

Fitter individuals more adapted to the environment have a better chance of survival, so can pass on advantageous alleles to future generations

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9
Q

Explain the process of evolution

A

A variety of phenotypes exist in a population due to random genetic mutation.
An environmental change occurs, leading to a new selection pressure.
Individuals with advantageous alleles give them a selection advantage, allowing them to survive and reproduce.
Advantageous alleles are passed to offspring, over time increasing frequency in the population.

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10
Q

What is the Hardy-Weinberg equation?

A

Used to estimate allele frequency in a population and monitor changes.
p^2 + 2pq + q^2 = 1
p^2 = dominant homozygous frequency (AA)
2pq = heterozygous frequency (Aa)
q^2 = recessive homozygous frequency (aa)

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11
Q

What are the conditions for the Hardy-Weinberg equation?

A 
No mutations
Random mating
Large population
Isolated population
No selection pressure
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12
Q

What is likely to occur when populations become isolated from one another?

A

New species will be formed due to accumulation of different genetic information in populations over time due to different environment and selection pressures

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13
Q

What is allopatric and sympatric?

A

Allopatric - When groups of organisms are geographically isolated
Sympatric - When groups of organisms are isolated by other means, in the same area

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14
Q

Explain the binomial system of classification

A

Homo sapiens

genus - species

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15
Q

How are organisms classified?

A

Kingdom, phylum, class, order, family, genus, species

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16
Q

What is molecular phylogeny?

A

The analysis of molecular differences in organisms to the extent of their evolutionary relationship

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17
Q

What is the three domain model?

A

Bacteria, archaea, and eukaryota

18
Q

How does the scientific community evaluate data?

A

Peer review of data of evidence, then publishing in scientific journals, where they are presented at scientific conferences

19
Q

Name 3 organelles present in plant cells and not in animal cells

A

Chloroplasts
Pits
Plasmodesmata

20
Q

Name another 3 organelles present in plant cells and not in animal cells

A

Cell wall
Amyloplasts
Vacuole

21
Q

Describe the function and structure of chloroplasts

A

Chloroplasts - Site of photosynthesis, bound by a double membrane called the envelope. They contain stacks of thylakoid membranes called grana, containing chlorophyll. Grana are connected by extensions of thylakoid membranes called lamellae, and are surrounded by a fluid called stroma, containing enzymes for photosynthesis.

22
Q

Describe the structure & function of:
Amyloplasts
Pits
Cell wall

A

Amyloplasts - surrounded by double membrane, contain amylopectin (starch) for storage, convert starch to glucose when required
Pits - Thin sections of cell wall which allow transport of substances between adjacent cells
Cell wall - Made of cellulose. Cell wall is made up of middle lamella, which is made of calcium pectate and holds adjacent cells, cellulose microfibrils and microfibers together

23
Q

Describe the structure & function of:
Vacuole
Plasmodesmata

A

Vacuole - Contains cell sap and is surrounded by a tonoplast (single membrane), providing cell support and strength
Plasmodesmata - An extension of cytoplasm between the cell wall of adjacent cells involved in transport of substances

24
Q

Define carbohydrate

A

Molecules which contain carbon, hydrogen and oxygen only

25
Q

Describe the structure of cellulose

A

Made of long, unbranched chains of beta glucose joined with glycosidic bonds. Microfibres formed of microfibrils are strong threads of long cellulose chains, joined together by hydrogen bonds for structural support.

26
Q

Describe the structure & function of xylem vessels

A

Transport water and minerals, also providing structural support. Long cylinders of dead cells with open ends, strengthened by lignin

27
Q

Describe the structure & function of phloem vessels

A

Tubes made of living cells involved in translocation of nutrients and food substances from leaves to storage organs

28
Q

What are cambium cells?

A

Cambium cells between xylem and phloem are undifferentiated and can specialize as the plant grows

29
Q

Describe the structure & function of sclerenchyma fibres

A

Short structures of dead cells with hollow lumen and end walls. Strengthened with lignin and provide structural support

30
Q

Describe the structure & function of parenchyma cells

A

Act as packing between other cells and vessels

31
Q

Describe 5 ways plant fibers can be used as a resource

A

Plants are a renewable resource, biodegradable, strong for use in rope or fabrics, cheaper production than oil-based, can be used in bioplastics/bioethanol

32
Q

Why is water needed in plants?

A 
Water is required for:
Structural rigidity
Photosynthesis
Transport of substances
Thermoregulation
33
Q

What are magnesium ions used for in plants?

A

They are involved in chlorophyll production and activate some plant enzymes

34
Q

What are nitrate ions used for in plants?

A

Supply nitrogen to produce DNA, RNA , and chlorophyll

35
Q

What are calcium ions used for in plants?

A

Component of cell wall, form calcium pectate, also essential for plant growth

36
Q

Explain the 3 stages of contemporary drug testing

A

Phase 1 - The drug is tested on a small group of healthy volunteers to test for dosage and toxicity
Phase 2 - The drug is tested on a large group of patients with the condition to test for efficacy
Phase 3 - Drug is tested against pre existing drugs with double-blinded trials to test for the placebo effect

37
Q

What is in-situ and ex-situ conservation?

A

In-situ is conservation in an organism’s habitat, ex-situ is outside an organism’s habitat

38
Q

Describe the method and pros of seed banks

A

Seed banks - Storage of a large number of seeds to conserve genetic diversity and prevent extinction. Since seeds are stored, less space is used and a larger number of species can be stored. They must be stored in cool, dry conditions and are periodically tested for viability

39
Q

Explain the method of captive breeding programs

A

Endangered species are bred to increase genetic diversity and population size via stud books, exchange of gametes, prevention of inbreeding, and IVF. Followed by reintroduction programs.

40
Q

Explain two in-situ methods of conservation

A

Education programs - aim to educate people about the importance of maintaining biodiversity, captive breeding programs and illegal trade of animal products.
National parks and Sites of Specific Scientific Interest aim to conserve habitats and biodiversity.

A-Level Biology Edexcel A (2 decks)

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