Investigating populations

Question 1

species

Answer 1

-closely related individuals which are capable of breeding
-to form fertile offspring

Question 2

population

Answer 2

-all the individuals of a given species living together in the same area at the same time

Question 3

carrying capacity

Answer 3

-the maximum equilibrium number of organisms of a particular species that can be supported indefinitely in each stable environment
-Birth rates death rates are in equilibrium

Question 4

community

Answer 4

-is all the individuals of all the species living together in the same area at the same time

Question 5

habitat

Answer 5

-place where an organism lives in an ecosystem

Question 6

niche

Answer 6

-describes where an organisms lives and what it does
-what it feeds on and how it interacts with other organisms and the environment

Question 7

biotic factors

Answer 7

-living factor which affects the distribution of an organism
-prey
-food availability
-disease

Question 8

abiotic factors

Answer 8

-a non-living factor which affects the distribution of an organism
-temperature
-light intensity
-wind speed

Question 9

conditions for estimating abundance

Answer 9

• data is not biased
  -selected at random
  -large sample must be taken
  -method for collection must be appropriate to the species

Question 10

Quadrats

Answer 10

-frame of known area which is placed on the ground and an estimate of the population sizes within them are made

Question 11

How is abundance of a species measured

Answer 11

-actual count of all individuals
-percentage cover
-frequency

Question 12

Using quadrats to find out the abundance

Answer 12

-use a grid
-use a random number generator to create co-ordinates
-plant quadrats in those co-ordinates
-count frequency of plants in quadrat
-calculate mean number per quadrat

Question 13

How to know how many quadrants are in

Answer 13

-calculate a running mean
-when enough quadrants, mean levels out
-enough to carry out. a statistical test
-use a large number to make sure results are reliable
-need to make sire work can be carried out in the time available

Question 14

Transect

Answer 14

recording what species are touching the line at each sampling point

Question 15

Belt transect

Answer 15

placing two parallel lines across, a metre apart and recording what species are found between the two lines

Question 16

interrupted belt transects

Answer 16

using one line and placing a quadrant down at equally spaced sampling point and recording abundance of species within the quadrant

Question 17

describe how you would investigate the distribution of marram grass from one side of the dune to the other

Answer 17

-transect the area from one side to the other
-place the quadrants at regular intervals along the line
-count plants in quadrants

Question 18

Mark-release-recapture

Answer 18

-animals of a particular species are ethically collected and counted
-animals are marked in some way
-animals are then released and left to redistribute into the population
-after a period of time a second capture is carried out
-total no. and marked no. are recorded

Question 19

population size formula

Answer 19

(n1 x n2)/Nm

Question 20

important considerations in MRR

Answer 20

• should be very few/no increase in birth/death/emigration/immigration rates
  -marking should not make the animals more susceptible to predators or harm AS the formula is based on the ratio of marked to unmarked indiv. remaining the same
  -the marking should not rub off or be lost
  -sufficient time should be left after release to be fully dispersed BUT not too long that death may occur

Question 21

MRR question points

Answer 21

-capture sample mark and release
-appropriate method of marking suggested
-take second sample and count marked organisms
-no in population=(no in sample 1 x no in sample 2) / no marked in sample two

Question 22

abiotic factor: temperature

Answer 22

-temp too cold then enzymes have too low kinetic energy to catalyse reactions quickly
-overall activity will drop and may not be sufficient for survival
-temp too high causes enzymes to denature
-overall activity will drop and may not be sufficient for survival
-temp can be measured using a thermometer

Question 23

abiotic factor: light intensity

Answer 23

-light needed for photosynthesis therefore the higher the intensity the more the growth via photosynthesis
-the more photosynthesis the more energy for spore production so increase in population
-the more the plants grow the more respiratory substrates is available for animal populations
-light intensity also effects leafing and flowering in plants along with reproductive cycles in animals
-water rapidly absorbs light

Question 24

abiotic factors: water availability and humidity

Answer 24

-a solvent in cells
-organisms tend to lose water via evaporation but for thermoregulation eg. sweating or mass transport
-the lower the humidity the more water loss will occur
-humidity is measured using a whirling hygrometer

Question 25

abiotic factors: pH

Answer 25

-the more extreme the pH the more the organism is affected and the lower the population size and range is
-pH can also affect the availability of mineral salts in the soil and therefore can affect growth in plants

Question 26

biotic factors: competition

Answer 26

• the more individuals present the grater the competition for the resources
  -competition increases when resources are limited
  -INTRASPECIFC= between same species
  -INTERSPECIFIC= between different species

Question 27

intraspecific

Answer 27

between same species

Question 28

interspecific

Answer 28

betwwen different species

Question 29

biotic factors: predators

Answer 29

-one animal species feeding on another
-evolved mechanisms to improve capturing such as high speed, venomous secretions
-prey have also evolved defence mechanisms eg. camouflage and protective spines