Populations In Ecosystems

Question 1

define ecosystem

Answer 1

all the organisms living in a community plus all the abiotic conditions in the area in which they live

Question 2

define community

Answer 2

a group of interacting populations of different species living in the same place at the same time

Question 3

define population

Answer 3

a group of organisms belonging to the same species found in the same area at the same time and potentially able to interbreed

Question 4

define habitat

Answer 4

the environment in which an organism or population of organisms usually live

Question 5

define biotic

Answer 5

the living features of an ecosystem e.g. the presence of predators or food

Question 6

define abiotic

Answer 6

the non-living features of an ecosystem e.g. temperature and the soil

Question 7

define niche

Answer 7

the role of a species within its habitat e.g. what it eats, when and where it feeds

Question 8

explain competitive exclusion

Answer 8

if 2 species try to occupy the same niche, there will be competition. one species will be more successful and survive and reproduce

Question 9

define adaptation and whats it caused by?

Answer 9

-a characteristic that members of a species have that increase their chance of survival and reproduction
-caused by random and spontaneous mutations

Question 10

define natural selection

Answer 10

when adaptations become more common in a population increasing allele frequency

Question 11

define carrying capacity

Answer 11

the max population size that can remain sustainable in an ecosystem

Question 12

give an example on the effect of abiotic factors on plants

Answer 12

a plant will grow much quicker if there is a higher temperature, higher light intensity, water and space available

Question 13

how might a abiotic factor of colder temp effect mammals?

Answer 13

-having the use a lot of energy to maintain the correct body temperature
-so less energy available for growth so slower growth
-less reproduction
-so population size will decrease

Question 14

what are the 3 main types of biotic effects that can influence population?

Answer 14

1. interspecific competition
2. intraspecific competition
3. predation

Question 15

describe interspecific competition

Answer 15

-competition that occurs between different species
-can be competing to occupy the same niche
-one species will have a competitive advantage = competitive exclusion principle

(inter= think intergalactic (outside different) from beastie boys)

Question 16

describe intraspecific competition

Answer 16

-competition between members of the same species
-causes fluctuations in population size around the carrying capacity = cyclical pattern
-as population increase, there are less resources for a larger population
-more intraspecific competition so now less food/energy for growth and reproduction
-population decreases so recourses increase
-less intraspecific competition
-more food/energy for growth and population so population increases

Question 17

describe predation on population size

Answer 17

-predation is where a predator kills and eats its prey.
-prey and predator pop sizes are inter-linked
-the relationship between them creates a selection pressure
-means those members of the species that are better adapted to hide or escape from predators are more likely to survive and reproduce

Question 18

why will predators never have higher population than prey?

Answer 18

biomass is lost so less energy to grow and reproduce

Question 19

what’s the advantage in knowing cyclical predation patterns?

Answer 19

carry out research at a more advantaged time when populations are higher

Question 20

why do we use logs?

Answer 20

-compare values with a very large range
-diff to plot on y axis
-to find the original value
-values in order of magnitude not numbers

Question 21

what does the log10 number tell you?

Answer 21

how many times 10 has been multiplied by itself to give that value

Question 22

factors 2 effecting bacteria growth

Answer 22

food and space available

Question 23

whats a broth culture?

Answer 23

a liquid broth containing bacteria

Question 24

whats a liquid broth?

Answer 24

a liquid containing nutrients a bacteria needs to grow

Question 25

how can we messure how much bacteria is present in a broth

Answer 25

-colorimeter to meassure light that can pass through.
scattered because bacteria is present
the more bacteria present, the more light is absorbed so higher absorbance value (less light transmitted)

Question 26

what type of graph is an absorbance against time?

Answer 26

exponential
-it shows the bacteria doubling at certain intervals of time

Question 27

define abundance

Answer 27

the number of individuals of one species in a particular area

Question 28

2 ways abundance can be measured

Answer 28

frequency- number of samples a species is recorded in
percentage cover- how much of the area is covered

Question 29

define distribution

Answer 29

how a species is spread across a habitat

Question 30

describe how to carry out random sampling

Answer 30

1.randomlu place quadrats using coordinates from a random number generator
2.count the total number in many quadrats
3. multiply to give estimate for total area

Question 31

give advantages of random sampling

Answer 31

-larger sample more representative
-random so prevents any bias
-saves time

Question 32

whats a quadrat?

Answer 32

frame made of small dividing sqaures in a larger square
investigates slow moving/non-motile

Question 33

what 3 things can quadrats messure?

Answer 33

1.species frequency = counting. shows likelihood of the species occuring
3. number of individuals = time-consuming.
4. percentage cover = count number of squares covered, include if more than half square covered. calculate a percentage

Question 34

what are the 2 types of transects?

Answer 34

1. belt transect = quadrats are placed next to each other along the line. can calculate species frequency and percentage cover
2. interrupted belt transects = place quadrats at regular intervals along the line

Question 35

give 4 examples for methods of investigating motile populations

Answer 35

-sweeping nets
-pooters/fall traps
-baited traps
-tranquilizers

Question 36

equation for total population size

Answer 36

(Number in 1st sample x number in 2nd sample)
divide
number marked in 2nd sample

Question 37

examples of making non-toxic

Answer 37

-non-toxic paint
-using tags
-cut thier hair
-dna samples

Question 38

principles of mark-release-recapture

Answer 38

1. marked sample needs enough time to mix with the non-marked population
   2.the marking not affected chance of survival
2. no population size changes dues to births, deaths and migration

Question 39

give 2 ethical issues in mark-release-recapture

Answer 39

1.organism could be stressed after being captured so could lead to a reduce in chance of survival
2. some organisms may be more likely to enter a trap again if previously caught