Populations

Question 0

Define population

Answer 0

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

Question 1

Define ecosystem

Answer 1

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

Question 2

Define community

Answer 2

The total population in a habitat

Question 3

Define habitat

Answer 3

Where the organism is normally found

Question 4

Define niche

Answer 4

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

Question 5

Define abiotic

Answer 5

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

Question 6

Define biotic

Answer 6

The living features within an environment eg predators or food

Question 7

Define adaptation

Answer 7

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)

Question 8

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

Answer 8

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.

Question 9

Examples of adaptations to abiotic conditions

Answer 9

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

Question 10

Examples of adaptations to biotic conditions

Answer 10

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

Question 11

Define abundance

Answer 11

The number of individuals of one species in a particular area

Question 12

Define frequency

Answer 12

The number of samples a species is recorded in

Question 13

Define percentage cover (for plants only)

Answer 13

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

Question 14

Define distribution

Answer 14

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

Question 15

How would you carry out a random sample

Answer 15

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

Question 16

Quadrats and transects are used to investigate…..

Answer 16

Plant populations

Question 17

Quadrats info

Answer 17

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

Question 18

Transects info

Answer 18

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

Question 19

Beating trays are used to investigate….

Answer 19

Insects found in vegetation

Question 20

Beating trays info

Answer 20

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

Question 21

Mark release recapture used to measure the abundance of ….

Answer 21

More mobile species

Question 22

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

Answer 22

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

Question 23

Ethical issues to consider when doing fieldwork

Answer 23

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

Question 24

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

Answer 24

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

Question 25

What is interspecific competition

Answer 25

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.

Question 26

What is intraspecific competition

Answer 26

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

Question 27

What is predation

Answer 27

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

Question 34

Describe stage 2 of the DTM

Answer 34

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

Question 35

Describe stage 3 of DTM

Answer 35

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

Question 36

Describe stage 4 of DTM

Answer 36

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

Question 37

Describe stage 5 of the DTM

Answer 37

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

Question 38

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

Answer 38

Population growth curves, survival curves, age population pyramids

Question 39

Population growth curves info

Answer 39

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

Question 40

Survival curves info

Answer 40

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

Question 41

Define life expectancy

Answer 41

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

Question 42

Age population pyramids info

Answer 42

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

Question 43

Human population growth is calculated using...

Answer 43

Birth and death rates

Question 44

Define birth rate

Answer 44

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

Question 45

Define death rate

Answer 45

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

Question 46

What is population growth rate

Answer 46

How much the population size increases or decreases in a year

Question 47

The demographic transition model shows

Answer 47

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

Question 48

Describe stage 1 of the DTM

Answer 48

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

Question 49

Pitfalls and pooters are used to investigate...

Answer 49

Ground insects