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A2 Biology UNIT 4 > Populations > Flashcards

Populations Flashcards

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0
Q

Define population

A

All the living things of the same species in a habitat at any one time

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1
Q

Define ecosystem

A

A stable, settled unit of nature consisting of a community of organisms, interacting with each other and with their surrounding physical and chemical environment

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2
Q

Define community

A

The total population in a habitat

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3
Q

Define habitat

A

Where the organism is normally found

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4
Q

Define niche

A

The role of a species within its habitat. This includes biotic interactions like what it eats and those it’s eaten by. Also includes its abiotic interactions like the oxygen an organism breathes in and the carbon dioxide it breathes out

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5
Q

Define abiotic

A

The non-biological features within an environment eg temp, light

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6
Q

Define biotic

A

The living features within an environment eg predators or food

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7
Q

Define adaptation

A

A feature that members of a species have that increases their chance of survival and reproduction. Can be physiological (process inside body), behavioural (way organism acts) or anatomical (structural features of body)

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8
Q

A niche can only be occupied by …. species. Why?

A

1
It may look like 2 species are filling same niche but there will be slight differences. If 2 species try to occupy the same niche, they will compete with each other, one species will be more successful until only 1 species is left.

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9
Q

Examples of adaptations to abiotic conditions

A

Otters have webbed paws-means that they can walk on land and swim. Increase chance of survival as they can live and hunt both in and out of water.

Whales have thick layer of flubber-keeps them warm in coldest seas. Increases chance of survival as they can live in places where food is plentiful

Brown bears hibernate-they lower their metabolism over winter. Increase chance of survival as they can conserve energy during coldest months

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10
Q

Examples of adaptations to biotic conditions

A

Sea otters use rocks to smash open shellfish and clams. Increases chance of survival as gives them access to another food source

Some bacteria produce antibiotics-kill other species of bacteria in same area. Increases chance of survival due to less competition for resources

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11
Q

Define abundance

A

The number of individuals of one species in a particular area

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12
Q

Define frequency

A

The number of samples a species is recorded in

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13
Q

Define percentage cover (for plants only)

A

How much of the area you’re investigating is covered by a species

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14
Q

Define distribution

A

Where a particular species is within the area you’re investigating

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15
Q

How would you carry out a random sample

A

Choose an area to sample, a small area within the area being investigated
Should be random to avoid bias, could use a random number generator
Use an appropriate technique to take a sample of the population
Repeat process, take as many samples as possible= more reliable estimate for whole area
The number of individuals for the whole area can be estimated by taking an average of data collected in each sample and multiplying it by the size of whole area. Percentage cover for whole area can be estimated by taking average of all samples

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16
Q

Quadrats and transects are used to investigate…..

A

Plant populations

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17
Q

Quadrats info

A

Square frame divided into grid of 100 smaller squares by strings attached across frame. They are placed on ground at different points within area being investigated. Species frequency or number of individuals of each species recorded in each quadrat. Percentage cover can also be measured by counting how much of the quadrat is covered by the species. Quadrants useful for quickly investigating areas with plant species that fit within a small quadrat, areas with larger plants and trees need a very large quadrat

18
Q

Transects info

A

Lines which help to find out how plants are distributed across an area. 3 types…
Line transects-tape measure placed along transect and species that touch tape measure are recorded
Belt transects-quadrats placed next to each other along transect to wrk out species frequency and percentage cover along transect
Interrupted transects-instead of investigating the whole transect of either a line or belt, you can take measurements at intervals

19
Q

Beating trays are used to investigate….

A

Insects found in vegetation

20
Q

Beating trays info

A

A tray or sheet held under a plant or tree. Plant or tree shaken and a sample of insects falls onto the beating tray. Can take large samples, giving good estimates of abundance of each species. However sample may not be random as most of it will be made up of insects that fall easily when vegetation shaken

21
Q

Mark release recapture used to measure the abundance of ….

A

More mobile species

22
Q

Risk assessments are carried out to ensure fieldwork is done in the safest way possible. What are some examples

A

Falls and slips- wear suitable footwear for terrain, take care on rough terrain, make sure study isn’t near any cliffs or on steep ground

Bad weather- check weather forecast beforehand and take precautions eg wear warm or waterproof clothing

Stings and bites- wear insect repellent or if you have an allergy take medication with you

23
Q

Ethical issues to consider when doing fieldwork

A

All fieldwork affects environment eg lots of people waking causes soil erosion. Investigations should be planned to have the smallest impact possible

Can affect organisms being studied eg capturing may cause distress. Investigating should be planned so organisms treated with great care and kept and handled as little as possible. Should be released as soon as possible after being captured

24
Q

The population size of any species varies because of which factors? Examples

A

Abiotic….
When these conditions are ideal for species, organisms grow faster and reproduce successfully
Eg when temp of mammals surrounding ideal don’t have to use up as much energy maintaining body temp. more energy for growth and reproduction so population size increases

When these conditions aren’t ideal, can’t grow as fast or reproduce as successfully
Eg if temp of mammals surroundings s much lower or higher than optimum, have to use more energy to maintain temp. Less energy available for growth and reproduction. Population size decreases.

AND biotic
Interspecific and intraspecific competition

25
Q

What is interspecific competition

A

Competition between different species. Can mean resources available to both populations are reduced so less food meaning less energy for growth and reproduction so population sizes lower for both species. If 2 species competing but one better adapted to its surroundings than other, the less well adapted species likely to be out-competed, won’t be able to exist alongside better adapted species.

26
Q

What is intraspecific competition

A

Competition within a species. Population of species increases when resources plentiful. As population increases=more organisms competing for same amount of space and food. Eventually resources such as food and space become limiting=isn’t enough for all organisms so population begins to decline. A smaller population means there’s less competition which is better for growth and reproduction so population starts to grow again

27
Q

What is predation

A

Where an organism (the predator) kills and eats another organism (prey). The population sizes of predators and prey are interlinked, as population of one changes, it causes other population to change

34
Q

Describe stage 2 of the DTM

A

Death rate falls due to better healthcare and sanitation, birth rate remains high. Population increase rapidly

35
Q

Describe stage 3 of DTM

A

Birth rate falls rapidly, death rate falls more slowly. Population increases at slower rate

36
Q

Describe stage 4 of DTM

A

Birth rate and death rate fluctuate at low level. Population remains stable but high. Birth rate stays low as an increased demand for luxuries and material possessions so less money available to raise children. They are not needed to work to provide income so parents have fewer children

37
Q

Describe stage 5 of the DTM

A

Birth rate begins to fall, death rate remains stable. Population begins to decrease. Birth rate falls as children expensive to raise. Death rate remains steady despite continued healthcare advances as larger generations of elderly people die

38
Q

Human population data can be plotted in 3 different ways which are…

A

Population growth curves, survival curves, age population pyramids

39
Q

Population growth curves info

A

Example =DTM. Made by plotting data for population size against time. They show whether the population was increasing or decreasing by the direction of the curve. The steepness of the curve shows how fast the population was changing

40
Q

Survival curves info

A

Show the percentage of all individuals that were born in a population that are still alive at any given age. This gives a survival rate for any given age

41
Q

Define life expectancy

A

The age that a person born into a population is expected to live to, worked out by calculating the average age that people die

42
Q

Age population pyramids info

A

Show population structure. Show how many males and females there are in different age groups within a population

43
Q

Human population growth is calculated using…

A

Birth and death rates

44
Q

Define birth rate

A

The number of live births each year for every 1000 people in the population

45
Q

Define death rate

A

The number of people that die each year for every 1000 people in the population

46
Q

What is population growth rate

A

How much the population size increases or decreases in a year

47
Q

The demographic transition model shows

A

Trends in human populations. It is a graph that shows changes in birth rate, death rate and total population size for a human population over a long period of time. It is divided into 5 stages

48
Q

Describe stage 1 of the DTM

A

Birth rate and death rate fluctuate at high level. Population stays low.

49
Q

Pitfalls and pooters are used to investigate…

A

Ground insects

A2 Biology UNIT 4 (10 decks)

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