Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key

image

Play button

image

Play button

image

Progress

1/34

Click to flip

34 Cards in this Set

  • Front
  • Back

define a habitat

A place where a community of organisms lives

Define ecosystem

Made up of all the interacting biotic (living) and abiotic (non living) features in a specific area

Define population

A group of interbreeding organisms of one species in a habitat

Define community

All the populations of different organisms living and interacting in a particular place at the same time

Define niche

An organisms role within the environment

Define ecology

The study of inter relationships between organisms and the environment

Define abiotic factors and give 3 examples

Non living


temperature


light intensity


oxygen availability


Altitude ( topography)


humidity


food availability

Define biotic factors and give 3 examples

Living factors


predation


pollution


disease


parasites


competition

Define abundance

The total number of individuals of a species within a given area

Give two ways abundance can be measured

Percentage cover - how much of the quadrat is covered


Frequency - how many of the quadrats the species occurs in

Name two sampling techniques

Random sampling (frame quadrats) or systematic sampling (along transects)

Describe the method of random sampling

lay out two tapes at right angles in the area of study


obtain a series of coordinates using random numbers (from calculator or computer)


place quadrat at coordinates


record species within it

Describe the method of systematic sampling along a transect

Lie tape across ground in a straight line


any organism over which the line passes is recorded

What is a belt transect

Two parallel lines normally a metre wide


species within the lines are recorded

Equation for population size (mark release recapture)

Estimated population = total number of individuals in the first sample x total number of individuals in the second sample



\ number of marked individuals recaptured

Describe the techniques of mark release recapture

A known number of animals are caught


they are marked in some way


they are released back into the community


some time later


a given number of individual is collected randomly


number of marked individuals is recorded

Mark release recapture relies on assumptions name 3

Proportion of marked to unmarked is the same in sample as it is in the population as a whole


marked individuals in the first sample distribute themselves evenly


the population has a definite boundary ( no immigration or emigration)


there are few if any deaths and births


method of marking is not toxic or makes indivula more liable to predation


mark is not lost or rubbed off


Describe the Population growth curves


(3 main features)

1. Slow growth- small number of individuals slowly reproduce


2. Rapid growth - ever increasing number of individuals continue to reproduce (gradient of curve is steep)


3. Population growth declines until size remains more or less stable (due to food supply or increased predation)

What happens to population size over time And why

Decreases due to limiting factors which causes population to slow/cease

Define intraspecific competition

Competition between members of the same species


eg food water breeding sites

Define interspecific competition

Competition between members of different species

Define predation

Where one organism consumes another

What is the main problem with investigating predation in a lab

In a lab the prey rarely escape whereas in the wild prey can escape so the population will fall low but rarely become extinct

Describe the effect of predator- prey relationships on population size


(5 points)

Predators eat prey reduce population size


fewer prey predators are in greater competition


predator population is reduced


Fewer predator, fewer prey eaten


prey population increase


predator population increases


(more food available)

Apart from predator prey relationships wha can effect population size

Disease and climatic factors

Factors that effect human populations

food availability


disease


predstors


climate


wars


birth rate


death rate

Define immigration

Where individuals join a population from the outside

Define emigration

Where individuals leave a population

Equation for population growth

(Births+ immigration) - (deaths + emigration)

Equation for population growth rate

Population change in period /. X100


population at start

Factors affecting birth rate (5 points)

Economic conditions - LEDC have higher birth rates


religion- some are opposed to birth control and some encourage larger families


social pressures - some cultures large families improves social standing


birth control - contraception and abortion


political factors - governments influence birth rates through education and taxation policies


Equation for birth rates

Total birth rates / total population x1000


Factors affecting death rates (7 points possible)

Age profile - more elderly means higher death rate


life expectancy at birth - economically developed countries live longer


Food supply


safe drinking water and sanitation


medical care


natural disasters


war

Equation for death rate

Number of deaths / total population x 1000