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SNAB A level Biology > Unit 4 > Flashcards

Unit 4 Flashcards

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1
Q

What is a niche?

A

the role of an organism within it’s community. A niche has boundaries and it’s role includes:

  • what it eats
  • what eats it
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2
Q

What is an ecological niche?

A

When both organisms share the same habitat and same food but hunt at different times, meaning they both survive

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3
Q

Name the 3 things there is competition for:

A
  • Territory
  • Mates
  • Resources
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4
Q

True or false: 2 species can occupy the same niche, habitat and resources?

A

No 2 species can occupy the same niche in the same habitat at the same time for the same resource

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5
Q

What is a species?

A

A group of organisms with similar morphology, physiology and behaviour which can interbreed to produce fertile offspring

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6
Q

What is a habitat?

A

the place where organisms live

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7
Q

What is a population?

A

a group of interbreeding individuals

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8
Q

What is a community?

A

all the organisms living in a habitat

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9
Q

Describe what a behavioural adaptation is and give an example:

A

A behavioural adaptation is an action by an organism which helps it survive or reproduce; an example is nocturnal animals

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10
Q

Describe what a physiological adaptation is and give an example:

A

A physiological adaptation is a feature of the internal working of organisms that help them to survive and reproduce; an example is scurvy grass

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11
Q

Describe what a anatomical adaptation is and give an example:

A

An anatomical adaptation is an adaptation we see when we observe or dissect organisms; an example is the pollen basket on the hind legs of bees

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12
Q

Explain evolution by natural selection

A

Organisms with better are adaptions will create a population with ideal characteristics as they’re more likely to survive, more likely to reproduce and more likely to pass on their advantageous alleles

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13
Q

What is evolution?

A

a change in allele frequency in a population over time

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14
Q

Is an organism more or less likely to survive if they’ve got non-advantageous alleles?

A

They’re less likely to survive

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15
Q

What is a gene pool?

A

The complete range of alleles in a population

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16
Q

When is the Hardy Weinburg equation valid?

A

When random mating occurs

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17
Q

What is the Hardy Weinburg equation?

A

P^2 + 2pq + q^2

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18
Q

What do the letters stand for in the Hardy Weinburg equation?

A 
P^2 = homozygous dominant
2pq = heterozygous / carrier
q^2 = homozygous recessive
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19
Q

The ability of a population to adapt to new conditions will depend on what things?

A
  • the reproductive rate of an organism
  • The strength of the selection pressure
  • the size of the gene pool
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20
Q

What has to happen for a new species to arise?

A

reproductive isolation

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21
Q

What is the most effective method of reproductive isolation?

A

A geographical feature such as high mountains as it prevents a group of individuals from breeding with the rest of the population.

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22
Q

What is speciation?

A

When two groups of organisms become less like each other due to selection pressures. They eventually may not be able to interbreed

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23
Q

What is biodiversity?

A

The richness and variety of life

24
Q

What is taxonomy?

A

The science of classification

25
Q

Why is classification of systems being constantly updated ?

A

More species are being created by mutations causing speciation

26
Q

What is the binomial naming system ?

A

A system that names species. It takes the genus and species e.g homo sapien

27
Q

What is phylogenetics?

A

The study of the evolutionary history of groups of organisms

28
Q

Who was Carl Woese?

A
  • was a scientist in 1960s to 1970s
  • he worked on evolutionary relationships in prokaryotes
  • he found an anomaly in methanogens
29
Q

List everything in the taxonomy hierarchy

A
  • Domain
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
30
Q

What are the 3 domains?

A

Bacteria, Archae and Eukaryota

31
Q

What is convergent evolution?

A

Where 2 organisms who are unrelated evolve similar adaptations due to selection pressure

32
Q

What is the diversity index equation ?

A

D=N(N-1) / Sigma n(n-1)

N=total number of organisms of all species

n=total number of organisms for each species

33
Q

Describe an endemic

A

A disease or condition found in a certain, small area

34
Q

Describe a pandemic

A

A disease or condition found in many regions or a large area

35
Q

What is genetic diversity ?

A

The total number of genetic characteristics in the genetic makeup of a species

36
Q

Describe species richness

A

The number of a species present in a given habitat

37
Q

Describe a genetic drift

A

The change in the allele frequencies over time and leads to reduction in genetic variation

38
Q

Explain inbreeding depression

A

In a small population there is a higher chance of inbreeding which causes recessive alleles. These alleles are harmful and can cause inbreeding depression

39
Q

Why are studbooks used?

A

They’re used to avoid inbreeding depression and loss of genetic variation by genetic drift

40
Q

What is a seed bank?

A

A seed bank stores seeds to preserve genetic diversity

41
Q

How should seeds be kept to ensure they stay usable?

A
  • dried
  • low humidity
  • stored at -20 degrees so plant growth is lowered due to metabolic rates as enzyme activity is lowered
42
Q

How often should seeds in a seed bank be tested?

A

They should be tested every 10 years for viability

43
Q

What are the aims of a captive breeding programme?

A
  • Increase the number of individuals of the species if numbers are low
  • Maintaining genetic diversity
  • Reintroducing animals into the wild
44
Q

True or false: Cellulose in a monosaccharide

A

False: Cellulose is a polysaccharide

45
Q

What monomer makes up cellulose?

A

Beta glucose

46
Q

What type of bonds are found in cellulose?

A

1-4 glycosidic

47
Q

How many glucose units are found in a cellulose chain?

A

1000 to 10,000 units

48
Q

Describe the formation of microfibrils

A

Hydrogen bonds form between the -OH groups in neighbouring cellulose chains

49
Q

What is the ‘glue’ that holds together microfibrils?

A

Pectin and hemicellulose

50
Q

True or false: hemicellulose and pectin are long, branched polysaccharides?

A

False: they are short, branched polysaccharides

51
Q

Where is pectin founds and what does it do?

A

It is found in the middle lamella and holds together the cell walls of adjacent cells

52
Q

What is in the vascular bundle?

A
  • Xylem
  • Phloem
  • Sclerenchyma
  • Parenchyma
  • Collenchyma
53
Q

Explain how the structure of the xylem is useful for its function

A
  • Lignified= strong and waterproofed

- Dead, hollow tubes=allow water to be drawn up by the transpiration stream

54
Q

Explain how the structure of the phloem is useful for its function

A
  • Sieve plates=strengthen and maintain shape

- Long columns=enable rapid transpiration

55
Q

Describe transpiration

A
  1. Water vapour diffuses out through the stoma down a diffusion gradient
  2. Water evaporates from the surface of cells
  3. Water replaced by capillary action in cell walls
  4. Water is drawn out the xylem
  5. A continuous column of water is drawn up through the xylem

SNAB A level Biology (8 decks)

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