12 Biodiversity

Question 1

Habitat

Answer 1

the place where an organism lives,

Question 2

Community

Answer 2

all the organisms (of different species) in a habitat

Question 3

Species Richness:

Answer 3

The number of different species in a habitat

Question 4

The diversity of a community reflects:

Answer 4

· the number of different species present

· the number of individuals in each species

Question 5

diversity index

Answer 5

N(N-1)
D = _______
S n(n-1)

Question 6

diversity index is Low value

Answer 6

Unfavourable/ harsh /agricultural land/ polluted habitat

· Few species present and often populations are small.
· Generally, abiotic (non-living) factors determine which species are present.
· Ecosystems in these environments are usually unstable.
· Only a few species are adapted to survive the harsh conditions (may be dominant)

Question 7

diversity index is high value

Answer 7

· Many species present & populations are usually large.
· Generally, biotic (living) factors, such as competition and predation, determine which species are present. · Ecosystems in these environments are usually stable.
· Complex food webs so a change in population of one species is less likely to affect other populations

Question 8

Random Sampling Method Using Quadrats

Answer 8

· A grid is laid out across the sample area using tape measures.

· A random numbers are generated (e.g. from a calculator or random number table) to provide coordinates on the grid. These are the sample points where a frame quadrat is placed.

· Within each quadrat the community is sampled, in this case each organism in the quadrat is identified and the number of individuals of each species is counted.

· As any one sample point is unlikely to be representative of the area, a large number of randomly placed quadrats are used.

· Mean number of each species can then be calculated.

Question 9

How does agriculture provide ideal conditions for crop photosynthesis, growth and harvesting maximum yield?

Answer 9

· Fertilisers added to provide minerals such as nitrates for growth.

· Fields irrigated so there is enough water.

· The crop species themselves are specially selected to grow well in the conditions provided (e.g. to make use of the fertiliser and grow fast to out compete weeds), and to provide high yields of useful product.

· Weeds, which are unwanted pants that would compete with the crop plants are removed / killed by using herbicides.

· Animal pests such as insects that would eat the crop plants are killed by insecticides.

Question 10

How and why does human activities, particularly agriculture, affect the species diversity of an area?

Answer 10

· Lowers species diversity

· A lower variety of habitats/ niches

· Fewer plant species because just one crop species grown and most weeds removed or killed by herbicides.

· Few species of herbivores as so little variety of plant food types.

· Fewer types of carnivore species because so few herbivore species to feed on.

· Use of pesticides will reduce diversity of insect species

Question 11

What is genetic diversity?

Answer 11

Genetic diversity refers to the number of different alleles of genes in a population.

Question 12

Causes of Genetic Diversity

Answer 12

· Mutations

· Meiosis

· Random fusion of gametes.

Question 13

Explain how a gene mutation could result in the production of a non-functioning protein.

Answer 13

· A gene is the sequence of bases in DNA that codes for the production of a protein.

· If the sequence of DNA bases is altered in a gene (i.e. due to mutation) then this will change the sequence of bases in the mRNA that is transcribed.

· This may change the sequence of amino acids in the protein.

· This change in the primary structure of the protein causes a change in the tertiary structure, as hydrogen, ionic and disulphide bonds form in different places

· This can lead to a loss or reduction in function of the protein.

Question 14

meiosis

Answer 14

watch yt video