last topic

Question 1

Describe:

Succession

Answer 1

Is the change in communities in area over time.
Primary succession- begins when there was no soil (volcano, glacier) and how species changes. Lichens->moss->grass
Secondary- when there was life before but due to natural disaster new species come up again.

Question 2

Describe:
Convergent-
Divergent-

Answer 2

Evolution of similar characteristics in species that are not closely related, observed in similar environments (pressure)

Evolution of different characteristics/species from a common ancestor, separated by speciation

Question 3

Describe:

Adaptive radiation:

Answer 3

Special case of divergent evolution where there is a sudden emergence of new species from common ancestor, such as darwin’s finches

Question 4

Describe:

Genetic drift-

Answer 4

Reduction of alleles/ genetic variation from small population due to certain individuals not surviving or reproducing. May result from disaster

Question 5

Describe:
Allopatric
Sympatric

Answer 5

Formation of new species from single population that becomes divided by geographical barrier.

Formation of 2 new species from common ancestor while in the same area with no barrier.

Question 6

Describe:

Gene pool

Answer 6

Total of all alleles of all individuals in a population of a species.
Larger gene pool means more genetic diversity, meaning species is more likely to survive selection pressures.

Question 7

Describe:
Reproductive isolation;
Prezygotic-
Postzygotic-

Answer 7

reproductive isolating Mechanism that prevents gene flow between populations.

Temporal (mating seasons/nocturnal), behavioural(mating calls), mechanical(genital difference), gamete(gametes may not recognise)

Post zygotic, 2 reasons, Hybrid inviability(zygote wont develop as genes too seperate), hybrid sterility (offspring is sterile)

Question 8

Describe:

Alleles

Answer 8

An alternative form of a gene for a particular characteristic

Question 9

Describe:

Endosymbiosis

Answer 9

When an organism live inside another and they both benefit

Question 10

Describe:

Natural selection:

Answer 10

Process which individuals in population who are better suited to environment tend to survive and contribute more genes to next generation, thus influencing characteristics of future generations.

Question 11

Describe:

Selection pressures

Answer 11

Sexually reproducing organisms have genetic variation due to
crossing over in meiosis in prophase 1
Also random selection of male/female gamete
Independent assortment

Question 12

Describe:

DNA hybridisation-

Answer 12

Technique to compare genome of different species to establish degree of similarity, and how related organisms are.
First heated, allow to separate into strands. Allow them to combine through cooling, than reheat to see which separates faster as closely related species will match well and require more heat.

Question 13

Describe:

DNA sequencing-

Answer 13

Technique which determines sequence of nucleotides in a DNA, can construct phylogenetic tree.

Question 14

Explain:

Phylogenetic tree

Answer 14

Depicts the evolutionary relationships between organisms and their common ancestors. Is dependant on the order you place them on the tree

Question 15

Describe:
Aibiotic
Biotic

Answer 15

Non-living factors and living factors

Question 16

Describe:

Biodiversity

Answer 16

The variety of organisms living in a region

Question 17

Describe:

Factors affecting genetic variation

Answer 17

mutation.
random mating between organisms.
random fertilization.
crossing over (or recombination) between chromatids of homologous chromosomes during meiosis, prophase 1

Question 18

Describe:

Bottleneck/founders effect

Answer 18

Much like genetic drift, a bottleneck would decrease the population of one species, lowering genetic variation meaning that the species is less able to cope with selection pressures.

Question 19

Describe:
Polyploid:

Answer 19

Polyploidy is a sympatric speciation which results when an organism has more than two sets of chromosomes. This occurs when chromosomes do not separate after duplication in mitosis and can be fertile.

Question 20

Describe:

Sequencing of proteins

Answer 20

Method for species comparison, compares similar proteins molecular structure from seperate species.

Question 21

Explain:

Why recently separated species have common DNA

Answer 21

It is likely that not enough time had passed for more than a few new mutations, thus DNA sequences should be similar.

Question 22

Describe:
Speciation:

Answer 22

process which gives rise to new species.

Allopatric/sympatric speciation leading from one species to split into two seperate species which cannot interbreed.

Question 23

Explain:

Natural selection results in evolution

Answer 23

By causing change in frequency of alleles in a population. Proportions of favourable genes will increase in a population due to natural selection. Which changes gene pool.

Question 24

Describe;

Importance of biodiversity

Answer 24

We get food, medicine, material from living things.
All life is interconnected. Reduction would have dire unexpected consequences.
Morality, we should not have the choice to kill

Question 25

Describe:

Evidence of prokaryotic cells before eukaryotic

Answer 25

Fossil record show cyanobacteria 3 billion years ago.while eukaryotes 1.6b ago.
Endosymbiosis suggests chloroplasts/mitochondria were free living prokaryotes.
Facts: double membrane, divide separately, circular DNA, ribosomes.

Question 26

Describe:

sources of genetic variation in a species that reproduces sexually

Answer 26

Crossing over in prophase 1 of meiosis
Independant assortment in metaphase 1
Fertilisation, random gamete

Question 27

Describe:

Criteria used to define a species

Answer 27

Sexual similarity, that they mate in the same manner
Morphological similarity, characteristics.
Biochemical similarity, DNA sequences.
Common gene pool, species is largest unit of population which genetic exchange is possible.

Question 28

Explain:

Human activities threatening species.

Answer 28

Removal of trees depletes habitat for animals in the community.
Acid rain affects water life that can’t sustain in certain pH
Increase CO2 causes global warming, increasing ocean levels and changing weather patterns.

Question 29

Describe:

Roles of RNA and ribozymes in first cells

Answer 29

RNA able to catalyse are ribozymes. As RNA is a simpler molecule, it is likely to have formed first. As it may replicate.

Question 30

Describe:

Summary of Natural selection

Answer 30

individuals in pop show phenotypic variation due to genotype difference that is inherited to next gen.
Selection pressures add “struggle for survival”
best adapted will survive and pass on
pop will evolve, natural selection measured by changes in freq of alleles in gene pool.

Question 31

Describe:

selective pressures

Answer 31

Biotic:
Predators, disease-causing organisms, competition, human activities
Abiotic:
Rainfall, Temperature, Nutrient levels, light intensity, drugs

Question 32

Describe:

Genetic drift again

Answer 32

Mechanism in which allele frequencies of a population may change over generations due to chance.
Bottleneck effect involves reduced population, resulting in less genetic diversity