Section 4 Diversity

Question 1

What is Biodiversity?

Answer 1

 variety in an ecosystem

 variety of habitats and variety of species

Question 2

What is Species Diversity?

Answer 2

 number of different species

 number of individuals for each species

Question 3

What is Genetic Diversity?

Answer 3

 variety of alleles in a species population

 the larger number of individuals in a species, the larger the genetic diversity

Question 4

Benefit of high species diversity?

Answer 4

 Stable ecosystem

 each species is less likely to become extinct (due to high genetic diversity)

 & if a species does become extinct it will not affect the food chain as there are other species available

Question 5

How to measure Species Diversity for an area?

Answer 5

 Species Diversity Index

 takes into account the number of different species and how many individuals there are for each species

 the larger the species diversity index, the larger the species diversity

Question 6

How does deforestation lower species diversity?

Answer 6

 (deforestation is the removal of trees for wood & space)

 decreases plant species diversity

 less variety of habitats

 less variety of food sources

 decreases animal species diversity

Question 7

How does agriculture/farming lower species diversity?

Answer 7

 deforestation to make space for farm

 only grow a few plants & keep a few animal species

 selectively breed plants & animals

 use pesticides to kill other species

Question 8

What is Classification?

Answer 8

placing organisms into groups

Question 9

What is Hierarchical Classification?

Answer 9

 large groups divided into smaller groups with no overlap

 domain, kingdom, phylum, class, order, family, genus, species

Question 10

What is Binomial Naming System?

Answer 10

 using Genus name and Species name to name organism

 Genus name first in capital, Species name second in lower case

Question 11

What is a Species?

Answer 11

a group of individuals with similar characteristics that can interbreed to produce fertile offspring

Question 12

Why are the offspring from 2 different species mating infertile?

Answer 12

 offspring will have a odd number of chromosomes

 therefore, cannot perform meiosis, cannot produce gametes

Question 13

What is Phylogenetic Classification?

Answer 13

based on evolutionary relationships – how closely related different species are and how recent a common ancestor they have

Question 14

DNA hybridisation (comparing the relationship between different species 1)

Answer 14

take DNA from 2 species to be compared
- radioactively label one of the DNA
- heat both sets so double strand separates
- cool so single strands join together
- look for Hybrid DNA (one strand from species A, one strand from species B)
- identify Hybrid DNA by 50% radioactivity
- heat Hybrid DNA to measure similarity
results = higher temperature

required more hydrogen bonds present more complementary base pairing

more similar the base sequence

more similar the species

more closely related

more recent a common ancestor

Question 15

AA sequence (comparing the relationship between different species 2)

Answer 15

: comparing AA sequence for the same protein (e.g. haemoglobin in mammals)

results = more similar the AA sequence

more similar the DNA base sequence
more similar the species
more closely related
more recent a common ancestor

Question 16

Protein shape (comparing the relationship between different species 3)

Answer 16

comparing shape of the same protein (e.g. albumin) using immunological technique

		- comparing species A and species B
		- take albumin from species A
		- place in a blood of rabbit
		- rabbit will make antibodies against 

albumin of species A

• takes these antibodies and place in blood from species B
• if the albumin in species B has a similar shape to species A,

the antibodies will bind to form antigen-antibody complexes,

this will then form a precipitate

				results     = 	more precipitate
					more complexes
					more similar shape
					more similar the species
					more closely related
					more common recent ancestor

Question 17

What is Variation?

Answer 17

difference in characteristics between organisms

Question 18

Types of Variation?

Answer 18

intraspecific = differences between organisms of the same species

interspecific = differences between organisms of different species

Question 19

Causes of Intraspecific Variation?

Answer 19

Genetic Factors = same genes but different alleles (allele are different type/forms of genes)

Environmental Factors

Question 20

Types of Characteristics?

Answer 20

Discontinuous and Continuous

Discontinuous: characteristics fall into certain groups with no overlap (e.g. blood group) – determined by genetics only (a single gene)

Continuous: characteristics show a range (e.g. height) – determined by genetics (a few genes, polygenes) and environment

Question 21

What is Genetic Diversity?

Answer 21

genetic variation, the variety of alleles within a population of a species

Question 22

Benefit of high genetic diversity?

Answer 22

species able to adapt with changes in the environment

e.g. if a new disease arises, some individuals will have characteristics to survive, and will reproduce passing on their alleles, so the species does not become extinct

Question 23

What can lower genetic diversity?

Answer 23

small population size (e.g. founder effect – where the numbers

start low, or genetic bottleneck – where the numbers decrease)

Question 24

What is natural selection and adaptation?

Answer 24

 variation in population of species
(genetic diversity/genetic variation/variety in gene pool)

 new alleles arise by random mutation

 environment applies a selection pressure on the
population

 those with favourable characteristics/favourable alleles/selection advantage/better adapted survive, the others die [natural selection]

 the ones that survive will reproduce, passing on their favourable alleles

 if this happens for many generations, then that characteristic will become most common – the allele will become more frequent [adaptation]

Question 25

What are the 2 types of selection?

Answer 25

stabilising and directional

Question 26

What is stabilising selection?

Answer 26

 when the environment favours those with the most common characteristic – those on the extreme dies out

 the common characteristic increases in proportion

 the range (standard deviation) will reduce

Question 27

What is directional selection?

Answer 27

 when the environment favours those individuals with characteristics on one of the extremes

 over time this will become the most common characteristic

 normal distribution will shift to that extreme

Question 28

What is a Gene?

Answer 28

 a section of DNA that codes for a protein

 made out of intron and exon

 intron = non-coding DNA (function e.g. turns gene on or off)

 exon = coding DNA (codes for protein)

Question 29

How does a Gene/Exon code for a Protein?

Answer 29

 made out of a sequence of bases

 each 3 bases code for 1 amino acid (called triplet code)

 therefore,

 sequence of bases

 determines sequence of triplet codes

 which determine the sequence of AAs

 = polypeptide chain/primary structure (folds to secondary, then to tertiary/quaternary)

Question 30

Favourable properties of triplet code?

Answer 30

 degenerate = each AA has more than one triplet code

 non-overlapping = each base is read only once

 stop codes = occur at end of sequence – do not code for an AA

Question 31

How does a mutation lead to a non-functional enzyme?

Answer 31

 change in base sequence

 change in sequence of triplet codes

 change in sequence of AAs

 change in primary structure

 change in hydrogen/ionic/disulfide bonds

 change in tertiary structure (3D shape)

 change in active site shape

 substrate no longer complementary

 can no longer form enzyme-substrate complex

Question 32

How is a protein assembled?

Answer 32

 by transcription and translation

 transcription = production of a single stranded complementary copy of a gene (called mRNA)

 translation = use sequence of codons on mRNA to assemble protein (tRNA brings in AAs)

Question 33

DNA vs RNA?

Answer 33

 deoxyribose sugar vs ribose sugar

 thymine vs uracil

 double stranded vs single stranded

 one type vs two types (mRNA and tRNA)

Question 34

What is a Chromosome Mutation?

Answer 34

 In plants, inherit more than one diploid set of chromosomes – called polyploidy

 In animals, homologous pair of chromosome do not separate in meiosis, so either inherit one extra or one less chromosome – called non-disjunction

Question 35

What is a Gene Mutation?

Answer 35

 a change in the base sequence of DNA

 2 types = substitution and insertion/deletion

 substitution = replace one base for another, changes one triplet code
can be silent (new triplet code codes for same AA), mis-sense (codes for a different AA, so protein shape changes slightly), non-sense (codes for a stop codon, so polypeptide chain not produced)

insertion = adding a base, deletion = removing a base
	both insertion/deletion causes frameshift, all the triplet codes after the mutation 			changes, so normal polypeptide chain/protein not produced