Module 3 (im tired)

Question 1

selection pressure

Answer 1

The way that some environmental factors differentially affect the survival and reproductive success of certain phenotypes in a population.

includes: predation, competition, disease, scarcity of food, temperature, weather conditions

Question 2

selecting agent

Answer 2

the specific factor that exerts the selective pressure

Question 3

selective advantage

Answer 3

An individual which has a feature that helps it to survive or reproduce under a selection pressure (compared to other members of the population) has a selective advantage.

Question 4

Structural: adapted to suit: hot weather conditions (plants)

Answer 4

Xerophytes:

• Fleshy stems / leaves that swell and retain moisture when it is available
• Shallow roots spreading across large areas to collect rainfall + deep roots to reach underground sources
• Spine-leaves reduced to decrease surface area to volume ratio, reducing water loss (less stomata)

Porcupine grass: Roll their leaves during hottest parts of the day so stomata are on the inside and not exposed to the dry atmosphere, creating a humid microclimate inside the leaf

Question 5

Structural: adapted to suit hot weather conditions (animals)

Answer 5

Thorny devil: - Layered scales creating a circulatory system on the surface of its skin – absorbs moisture by placing its leg in water / through dewy plants and pumps water through the grooves until getting to the mouth

Question 6

Physiological: adapted to suit cold conditions

Answer 6

Deciduous trees: lose their leaves in winter, produce organic compounds that act as anti-freeze
Tulip bulbs: vernalisation: produce a flower in response to low temps

Question 7

Physiological: adapted to suit high salinity

Answer 7

Halophytes:

• increase water content in large vacuoles
• bladder cells that excess sodium and chloride ions are transported into, burst when they reach capacity
• salt is secreted through glands on leaves
• salt can be excluded from entering roots

Question 8

Physiological: adapted to suit hot weather

Answer 8

spinifex hopping mouse: - Reduces water loss by excreting highly concentrated urine – able to reabsorb most of the water from their urine back into their bloodstream

Question 9

Behavioural: competition

Answer 9

Venus fly trap actively shuts when a small insect touches it

Question 10

Behavioural: temperature fluctuation

Answer 10

Low: lie in the sunlight and alter body position to expose more to the sun
high: retreat into shade of rocks or burrow

Question 11

natural selection

Answer 11

The key mechanism of evolution that is the differential survival and reproduction of individuals in a species, due to selective advantages and disadvantages by heritable difference in their phenotype.

Question 12

Allopatric speciation

Answer 12

occurs when two populations are geographically isolated from one another with an impassable barrier separating them (they can no longer breed together)

example: barrier formed between the Pacific Ocean and Caribbean Sea meant that populations of fish could no longer breed. They became subject to different selective pressures.

Question 13

sympatric speciation

Answer 13

occurs when two populations are within the same geographical area
o Prezygotic barriers: behavioural isolation, temporal isolation (breeding at different times of the year), habitat
o Postzygotic: the offspring is unable to reproduce, they are genetically weaker, not able to develop due to genetic incompatibility

Question 14

Types of sympatric speciation

Answer 14

Behavioural
Temporal
Mechanical / chemical
Habitat / ecological

Question 15

Divergent evolution

Answer 15

The pattern of evolution in which an ancestral species gives rise to two or more distinct species.

Question 16

Convergent evolution

Answer 16

A pattern of evolution in which under similar selection pressures, two unrelated species evolve similar adaptations independently.

Question 17

Punctuated equilibrium

Answer 17

• Punctuated Equilibrium: a theory in evolutionary biology that proposes that after a period of rapid evolution following a speciation event, a species becomes stable for a long period of time

Question 18

phylogentic gradualism

Answer 18

A model of evolution with continuous small changes within the population over a large expanse of time.

This accounts for microevolutionary changes.

Question 19

Biochemistry: DNA hybridisation

Answer 19

A method for comparing the degree of similarity between DNA from two species by joining (or hybridising) and testing how tightly joined they are.

• The DNA is heated, so the strands of each DNA sequence are separated, leaving 4 individual strands of DNA
• The DNA is cooled down to 55OC, allowing them to join back together
• Once the hybrid is formed, the temperature at which the DNA separates is measured

Question 20

Biochemistry: DNA and AA sequencing

Answer 20

Amino acid sequencing: the sequence of AA in the protein is analysed and similarities are identified. Increased similarity indicates that the species share a common ancestor.

DNA sequencing: The order of the nucleotide bases in the DNA of one species is compared with a similar fragment of another species. The more closely relate, the more similar the DNA sequence is.

Question 21

Comparative anatomy: homology

Answer 21

Structures which have the same ‘plan’ but serve a different purpose.
Example:
- Homology suggests that the various forelimbs found in land vertebrates represent modifications of a basic plan, inherited from a common ancestor (pentadactyl limb)

Question 22

analogous structures

Answer 22

• Analogous structures: structures which have the same function in different species, but their underlying anatomical plan is fundamentally different
• Wings are seen in bats, birds and insects – however the structure of the wings in each group are fundamentally different
• Like primates, pandas have an opposable thumb – but unlike primates, this is not one of the five digits but a modified ‘wrist’ bone

Question 23

comparative embryology

Answer 23

Comparison of development of embryos in closely related species. At different stages of development there are similar structures that exist in vertebrate embryos.

Question 24

fossil record (datin)

Answer 24

• Fossilisation typically occurs underwater, where the dead organism will be rapidly covered by sediment (prevents decay), and as more sediments increase pressure and turn to rock, a fossil occurs
• Law of superposition: the rock layers at the top are the youngest
• Overtime, there has been an increase in complexity of the organisms (vertebrates, humans, animals, etc  found only in the younger rock platforms)

Question 25

cane toad: effect on predators

Answer 25

• Snakes have evolved to have a smaller head as they are unable to eat large toads (i.e. Cane Toads) and will therefore be less susceptible to toxins exuded by these toads
• Crocodiles in the East Coast of QLD have become resistant to Cane Toad toxin due to being exposed to Cane Toads for a longer period of time. The ones that were most susceptible to the toxin died and therefore the concentration of toxin-resistant crocodiles increased.

Question 26

types of selection pressures

Answer 26

biological factors, resource availability, environmental conditions

Question 27

Biological factors:

Answer 27

introduction of myxomatosis virus

Question 28

envrionmental conditions

Answer 28

polar bears moving north