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AS Biology > Biodiversity > Flashcards

Biodiversity Flashcards

1
Q

Gene pool

A

All of the alleles of all the genes in a population

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2
Q

Gene pool constant

A

Population is not evolving

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3
Q

Gene pool changing

A

There are selection pressures and population is evolving

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4
Q

Species

A

A class of similar organisms that can interbreed freely, producing fertile offspring

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5
Q

Morphologically similar

A

Look similar

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6
Q

Homologous chromosomes

A

Have the same genes in the same places (different alleles)

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7
Q

Karyotypes

A

The number and appearance or chromosomes in a cell nucleus

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8
Q

Ecosystem

A

An area in which organisms interact with each other and their environment

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9
Q

Community

A

Entire set of organisms which coexist in a particular ecosystem at a particular time

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10
Q

Environment

A

The physical and biotic surroundings

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11
Q

Population

A

The total number of individuals of a species within a community in a particular ecosystem at a particular time

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12
Q

Habitat

A

An area within an ecosystem in which a particular organism lives

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13
Q

Niche

A

The way an organism uses its environment and its role in the community

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14
Q

Fundamental niche

A

Largest niche an organism could occupy if there was no competition

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15
Q

Realised niche

A

The niche that is actually occupied by the organism

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16
Q

Adaptation

A

When an organism involves its behavioural, physiological, anatomical features for survival in their habitat

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17
Q

Behavioural adaptations

A

Actions that help an organism survive within a habitat eg penguins huddle

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18
Q

Physiological adaptations

A

Features of the cells, tissues, or systems in the body in order for an organism to suit its habitat for survival eh whales thick blubber warm

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19
Q

Anatomical adaptations

A

Visible, physical features that enable an organism to survive better in their habitat eg Arctic hare small ears lose less heat

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20
Q

Co-adaptation

A

Mutual benefit of two or more organisms as a result of a mutual survival adaptation

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21
Q

Microevolution

A

A change in allele frequency in a population over time (which results in a change behaviour, psyiology, and/or anatomy)

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22
Q

What three factors determine the ability of a population to adapt to environmental change?

A
  • Strength of selection pressure
  • size of the gene pool
  • reproductive rate of organism
23
Q

Why is it unlikely that a population would be perfectly adapted to their environment?

A
  • Environments change continually
  • There is always a selection pressure
  • Time lag for populations (allele frequencies) to adapt
  • mutations occur (alleles making populations less well adapted)
24
Q

Why is it a problem to be perfectly adapted to an environment?

A
  • Dependence on other species- vulnerable if other species die out
  • Less likely to survive environmental change
25
Q

How can a new species form? (Speciation)

A
  • some individuals migrate to nearby islands
  • reproductive isolation of island communities
  • random mutations, some advantageous
  • different selection pressures experienced on each islands
  • some mutations are selected (in reproduction)
  • the island species are no longer able to produce fertile offspring with mainland population
26
Q

What causes allele frequencies to change?

A 
Mutations
Emigration/immigration 
Small populations (genetic drift)
Non-random mating
Natural selection
27
Q

Gene flow

A

The movement of genes from one population to another

28
Q

Genetic drift

A

Change in allele frequency that happens due to chance or random events

29
Q

What can cause genetic drift?

A

Founder effect, bottleneck effect

30
Q

What is the bottleneck effect?

A

When population rapidly reduces eg due to disease of natural disaster

31
Q

What is the founder effect?

A

New population is established with a different allele frequency

32
Q

Biodiversity

A

The number of different species and the genetic variation within species

33
Q

Endemics

A

Species that are unique to a geographic area (they provide much of the biodiversity on earth because of founder effects, isolation, bottle necks, other selection pressures)

34
Q

Species richness

A

The simplest measure of biodiversity (the number of species in a defined area)

35
Q

Species evenness

A

When species (at the same trophy level) have similar abundances

36
Q

Diversity index

A

A measure of biodiversity that takes into account both species richness and species evenness (can be used to compare habitats)

37
Q

Directional selection

A

Selection pressure favouring one extreme of a characteristic (other extreme selected against)

38
Q

Stabilising selection

A

Selection pressure that favours the mean (both extremes selected against)

39
Q

Disruptive selection

A

Selection pressure that favours both extremes (mean is selected against)

40
Q

Classification: taxonomic levels

A

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

41
Q

Chloroplasts structure and function

A

Double membrane and grana (singular granum)

Function: photosynthesis

42
Q

Amyloplasts

A

Store starch (potato cells have a lot of Amyloplasts)

43
Q

Vacuole

A

Stores water, plant pigments

The vacuole membrane is called tonoplast

44
Q

Plasmodesmata

A

Cytoplasmic streams between plant cells for the transport of molecules between cells

Formed by the ER getting stuck in cell wall as it forms and fills

45
Q

Pits

A

Pores in cell walls that allow movement of fluid between plant cells, especially xylem for transport of water

46
Q

Middle lamella

A

The layer between cell walls that helps to keep the cells together for stability (acts as a blue between plant cells)

Made of pectin

47
Q

Microfibrils

A

Each Microfibril has 60-70 cellulose chains

48
Q

How are microfibrils arranged

A

Microfibrils are laid down in different directions.

They make cell walls strong and flexible.

Cross-linking molecules also help to hold the cell wall together, while allowing a little stretch when the cell becomes turgid

49
Q

Epidermis

A

Single layer of cells on outside of plant

50
Q

Vascular tissue

A

For transport and support

51
Q

Ground tissue

A

Cells for photosynthesis, storage or support

52
Q

Parenchyma

A

(Big white cells in the middle)

Packing tissue, thin cellulose walls, provide support (eg palisade or spongy cells)

53
Q

Collenchyma

A

Below epidermis, tightly packed, thick cellulose walls, provides flexible support

54
Q

Sclerenchyma

A

(Small on outside of vascular bundle)

Dead cells when mature

Rigid, thick, lignified walls

Support plant - very strong
(Made up of sclereids and fibres)

AS Biology (4 decks)

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