Environmental interactions - ecology

Question 1

what is ecology?

Answer 1

the study of ecosystems

Question 2

what is an ecosystem?

Answer 2

an easily described system or area where organisms interact with their physical environment

Question 3

which components do all ecosystems include?

Answer 3

• producers
• consumers
• decomposers
• a physical environment
• range of different habitats

Question 4

what is a producer?

Answer 4

• organisms which make their own food (e.g. photosynthesising plant)

Question 5

what is a consumer?

Answer 5

• organisms which eat other living things (e.g. animals)

Question 6

what are decomposers?

Answer 6

• organisms which secrete digestive enzymes to decay (breakdown) dead organic matter to obtain their food; they help to recycle nutrients

Question 7

what is a physical environment?

Answer 7

• all the non-living (abiotic) factors which affect growth and survival of living things
• these include temperature, carbon dioxide and oxygen concentrations, minerals in the soil…

Question 8

what is a habitat?

Answer 8

• places where specific organisms live

Question 9

what is a population?

Answer 9

• the total number of individuals of one species in a particular habitat

Question 10

what do you use to measure the size of a population in a habitat?

Answer 10

• a quadrat
  to measure a population we:
• place it on the ground
• count the number of individuals of our chosen species inside the square

Question 11

what should you count if some individuals are on the edge of the quadrat?

Answer 11

• if they are half-in or half-out the quadrat, count those of the top and left edges only

Question 12

how would you find out the population of a species in a habitat?

Answer 12

• calculate the area of the habitat
• measure the number of individuals in one quadrat and repeat many times to check the result is reliable (at least 10 quadrats)
• calculate the average number of individuals in a quadrat
• calculate how many quadrats fit into the total area
• multiply how many quadrats fit into the total area by the average number of individuals in a quadrat

Question 13

what do we use to make sure our data is valid?

Answer 13

• random sampling
• means we are avoiding choosing areas which may be interesting as it would bias our result

Question 14

what do you do to take a random sample?

Answer 14

1. lay out two tape measures at right angles to make a 10m by 10m set f axes. Generate pairs of random numbers between 0 and 10 which are the coordinates
2. Use the coordinates to place the quadrat

Question 15

how do you do sampling ?

Answer 15

• grid - generate random numbers between 1 and 10 to use as coordinates
• place quadrat in bottom left corner of grid
• transect- sample continuously or at regular intervals along the line

Question 16

are habitats uniform?

Answer 16

• no
• there will be differences in abiotic conditions such as light intensity or one area may be trampled
• these differences could affect the distribution of our population

Question 17

what are the two ways in which you can investigate sampling in an ecosystem?

Answer 17

• pick two contrasting areas and set up a grid in each and use random sampling to take repeated measurements with a quadrat and compare the average results
• use a transect , a transect is a line across a habitat, which is placed to pass through a range of biotic or abiotic conditions (e.g. from light to shade, or across a path). a quadrat is placed at regular intervals along the transect and used to measure the number or % cover of the species.