Biodiversity

Question 1

Ehat is biodiversity?

Answer 1

The variety of living organisms living in a habitat/community.
Ot includes both genetic and species diversity.

Question 2

What is a habitat?

Answer 2

The place where an organism lives

Question 3

What is a community?

Answer 3

All the organisms of different species that live in a habitat

Question 4

What is species richness, and why is it not very useful for measuring biodiversity?

Answer 4

Species richness is the number of different species in a habitat.
However it does not take into account species eveness, so comparisons cannot be fairly made

Question 5

What is the species diversity index?

Answer 5

A number that describes species diversity, and reflects both the number of different species, and the abundance of individuals in esch species.

Question 6

What is the equation for species diversity index?

Answer 6

D= N(N-1) / {n(n-1)

Question 7

What two oieces of data need to be collected in order to calculate species diversity index?

Answer 7

N- total number of organisms of ALL species
n- total number of organisms in a PARTICULAR species

Question 8

What do high and low species diversity index numbers imply?

Answer 8

High- favourable, stable conditions. Large population with many different species. Complex food web. May biotic factors determine which species are present.

Low- unfavourable and unstable environment. Small population with little species. Abiotic factors determine which soecies present. Very few species are adapted to harsh conditions

Question 9

Give an example of where the soecies diversity index would be low

Answer 9

In agricultural management

Question 10

What is sampling?

Answer 10

Collecting a small bit of data that can be representative of a community as a whole

Question 11

Why is random sampling beneficial?

Answer 11

It ensures any bias is removes

Question 12

Describe an example of how you could collect data by using randomly placed quadrats

Answer 12

• A grid is laid across the sample area using tape measure
• Random numbers are generated to provide coordinates for the grid. A frame quadrant is then placed at these points
• Within each quadrant the community is sampled (each species is identified and the number of each species is counted)
• A large number of randomly placed quadrants are used, as one is unlikely to be representative of an area.
At least 20 quadrants should be used to be able to do any statistical analysis of the results.

Question 13

What is genetic diversity?

Answer 13

The number of different alleles of a gene in a population

Question 14

What is a gene?

Answer 14

A section of DNA bases that codes for a polypeptide

Question 15

What is an allele?

Answer 15

A different version of a particular gene

Question 16

What is the gene pool?

Answer 16

The set number of alleles within any one species. The bigger the gene pool the more genetic variation there is between that species

Question 17

Why are species with a larger gene pool more likely to survive a change in environment?

Answer 17

They have more genetic variation between individuals, so are more likely to be able to adapt to the change. Specifoc alleles may increase in proportion over time if they cause changes in survival and reproduction

Question 18

State the three main causes of genetic diversity

Answer 18

Mutations
Meiosis
Random fusion of gametes

Question 19

Explain what a mutation is

Answer 19

A mutation is a change to the sequence of DNA bases in an organism.

Question 20

How can a mutation lead to the production of a non functioning protein?

Answer 20

Sequence of DNA bases in a gene change, so the sequence of bases in the mRNA that is transcribed changes.
This may lead to a change primary structure in the protein
Bonds then from in different places, so tertiary structure changes.
Causes loss lf function

Question 21

What is monoculture?

Answer 21

A syetsm where existing vegetation is removed and the growth of only one crop species is introduced.

Question 22

In monoculture, how are ideal conditions for growth created?

Answer 22

Fertilisers added to provide minerals for growth.
Fields are irrigated to provide enough water
Weeds and animals that prevent growing/compete for resoirces are removed
Plants chosen to grow that are already specialised to grow in existing conditions.

Question 23

In monoculture, how can weeds and pests be removed?

Answer 23

Being physically picked out
Chemical herbicides can remove weeds
Hedgegrows can be removed to remove habitats
Animal pesticides that are toxic chemicals tha5 kill a wide range of animals are used

Question 24

How does the removal of crops and pests decrease species diversity?

Answer 24

Less plants- less food for herbivores- less food for carnivores- decreases population of most animals
Lower variety of habitats for animals decreases biodiversity
Lowered biodiversity of insetcts as pesticides are used

Question 25

State five ways to introduce a balance between farming and conservation

Answer 25

Planting hedgerows
Maintaining/creating ponds where possible
Plant native trees in areas of low species diversity
Use organic fertilisers
Use a crop rotaion that used a nitrogen-fixing crops to improve soil fertility without the need of fertilisers

Question 26

Homologous chromosomes are not genetically identical, why?

Answer 26

The carry the same genes, yet different alleles

Question 27

What are gametes?

Answer 27

Haploid cells, so they contain half the number of chromosomes as a normal cell. Produced during meiosis

Question 28

What is the process of meiosis?

Answer 28

Starts with a diploid parent cell, that has one pair of homologous chromosomes
Each chromosome contains a pair of chromatids, held by a centromere. This is a result of DNA replication during interphase
During the first division, homologous pairs separate and the cell becomes haploid
In the second division, the centromere breaks and the chromatids separate to produce half the number of chromosomes.

Question 29

What is chromosome non- disjunction , and what can it cause?

Answer 29

A process that causes a cell to have an extra copy of a particular chromosome.
Homologoud chromosomes don’t separate properly, so both chromosomes of a homologous pair go onto the same gamete.

This can cause down syndrome

Question 30

State two ways in which meiosis can lead to variation

Answer 30

Independent segregation
Crossing over

Question 31

Explain how independent segregation leads to variation

Answer 31

When homologous chromosomes line up along the equator, their orientation is completely random.
Sl separation of these pairs results in different combinations of maternal and paternal chromosomes in each gamete

Question 32

Explain how crossing over can cause variation

Answer 32

At the start of meiosis, homologous pairs of chromosomes associate to form a bivalent. One chromatid from each chromosome wrap around eachother at points called charismata.
This causes sections of each chromatid to break of and join the other.
Therefore alleles are exchanged between the maternal and paternal chromosomes

Question 33

What are differences between meiosis and mitosis?

Answer 33

Mitosis has one cell division, meiosis has two
Mitosis forms two daughter cells, meiosis forms four
In mitosis the number of chromosomes remains, it meiosis it halves
Mitosis forms identical cells, meiosis creates variatiom
Mitosis does not have pairing of homologous chromosomes, meiosis does