populations in ecosystems

Question 1

what is a species?

Answer 1

a group of organisms that share a gene pool and have similar characteristics and can breed to produce fertile offspring

Question 2

what is a habitat?

Answer 2

the place in which an organism lives

Question 3

what is a population?

Answer 3

a group of organisms of the same species living in the same habitat at the same time

Question 4

what is a community?

Answer 4

all of the populations of different species that interact in the same habitat

Question 5

what is a niche?

Answer 5

describes how an organism fits into its environment - where it lives and what it does there. it includes the biotic and abiotic conditions to which an organism is adapted in order to survive and reproduce

Question 6

what is an abiotic factor?

Answer 6

non living components of the environmentw

Question 7

what are some examples of biotic factors?

Answer 7

food availiability, prey, predators, competition, available mates

Question 8

what is a biotic factor?

Answer 8

living components of the environment and their interactions

Question 9

what are some examples of abiotic factors?

Answer 9

humidity, temperature, wind speed, light intensity, soil pH

Question 10

what is an ecosystem?

Answer 10

a dynamic system made up of a community and all of the interacting biotic and abiotic factors in that area

Question 11

what is carrying capacity?

Answer 11

the maximum population size that can be supported by the ecosystem

Question 12

what is the lag time on a growth curve showing?

Answer 12

• there is slow replication
• getting used to conditions (e.g. by making enzymes)

Question 13

what is the log time on a growth curve showing?

Answer 13

• fast replication
• optimum conditions (e.g. lots of oxygen, glucose)

Question 14

what is the stationary phase on a growth curve showing?

Answer 14

• little/no replication
• lack of glucose/oxygen
• too high temp / wrong pH

Question 15

what is the carrying capacity?

Answer 15

the maximum population size that can be supported by an ecosystem

Question 16

what are the two types of competition?

Answer 16

interspecific and intraspecific

Question 17

what is interspecific competition?

Answer 17

competition between different species

Question 18

why is it important to sample randomly?

Answer 18

to avoid any bias

Question 19

how would you make a sample more representative?

Answer 19

by using more quadrats

Question 20

what are the two ways of measuring abundance?

Answer 20

• frequency
• % cover of area

Question 21

what is the method for random sampling?

Answer 21

1/ divide sampling area into a grid and use a random number generator to give coordinates
2/ at each coordinate place the quadrat and record the %cover of plantain in the quadrat (can be changed for number of the organism)
3/ repeat for 20 quadrats and calculate a mean
4/ multiply the mean by the number of quadrats that would fit into the whole field

Question 22

when would you use a transect?

Answer 22

used to study the DISTRIBUTION of a species
if we think an abiotic factor changes across a habitat and this affects the living species

Question 23

how to carry out a practical with a transect?

Answer 23

lay a tape measure across the habitat and at set intervals place the quadrat down and record the number/%cover of a species
at each sampling point also record the abiotic factor
repeat 2 more times parallel to the first transect

Question 24

summarise the relationship between predators and prey?

Answer 24

• predators eat prey , reducing pop size
• fewer prey available , so more competition between predators
• predator pop reduced as some unable to get prey
• fewer predators left , soprey pop size increases
• more prey available , so predator pop size increases

Question 25

what are confounding variables?

Answer 25

variables that we cannot control, but it may affect our dependent variable

Question 26

what are examples of confounding variables in sampling practicals?

Answer 26

soil ph, temperature, soil moisture content