Classification and Evolution part 2

Question 1

What does a low standard deviation indicate

Answer 1

it indicates that the data collected has a narrow range and the points are closely grouped to the mean, therefore there is greater reliability

Question 2

What does a high standard deviation indicate

Answer 2

A high standard deviation indicated that the data points have a larger range and are less well grouped, therefore there is a lower reliability

Question 3

What does a T test do

Answer 3

• it compares two means, and it sees if you can agree with the null hypothesis or not
• if the T test bigger than the critical value then reject the null hypothesis
• if the t test is smaller than the critical value then accept the null hypothesis

Question 4

how to work out the degree of freedom

Answer 4

sample size- number of means

Question 5

Draw T test formula

Answer 5

Draw it

Question 6

What is adaptation?

Answer 6

a characteristic that enhances survival in a habitat

Question 7

What is a well adapted organism adapted to do?

Answer 7

• find enough food or photosynthesis well
• find enough water
• gather enough nutrients
• defend against predators and diseases
• survive the physical conditions of its environment for example temperature light
• respond to change in the environment
• have sufficient energy to allow for successful reproduction

Question 8

What is Marram Grass

Answer 8

specialised plant that has adapted to living on sand dunes, it has to be able to take as much water in as possible therefore it is an xerophyte

Question 9

What is anatomical adaptations

Answer 9

Any structural features that enhance the survival of the organism

Question 10

Describe how Marram Grass is anatomically adapted?

Answer 10

• long roots - enables plant to reach water deep underground
• roots also spread out over a wide area - absorb a lot of water and helps stabilise the sand dunes in which the plant lives
• Curled leaves - this reduces surface area exposed to the wind and traps air inside against the lower epidermis therefore this increases the moisture that is there and creates a shallow water potential gradient
• Lower epidermis is covered in hairs - reduces air movement so that water vapour is retained closer to the lower epidermis
• Lower epidermis is folded to create pits where the stomata are - water vapour builds up in the pits this reduces the loss of water vapour as shallow water potential gradient created
• Low density of stomata - fewer stomata so less water lost
• Leaf in Waxy cuticle layer - reduces water evaporation from the cells of the leaf

Question 11

What are behavioural adaptations?

Answer 11

The ways in which behaviour is modified for survival in the conditions that it lives in

Question 12

Give some examples of behavioural adaptations

Answer 12

• when you touch an earthworm it curls up and withdraws into it burrow - this is to avoid being eaten
• marram grass responds to shortage of water by rolling up its leaf more tightly and closing the stomata this reduces the transpiration rate
• when covered by sand marram grass will grow more quickly to reach sunlight

Question 13

What are physiological and biochemical adaptations

Answer 13

Any adaptation that ensures the correct functioning of cell processes, that enhance the survival of the organism

Question 14

Give an example of physiological and biochemical adaptations

Answer 14

Yeast - Saccharomyces can respire sugars aerobically and anaerobically depending on how much oxygen is present

Question 15

Explain Marram Grass physiological and biochemical adaptations

Answer 15

• the ability to roll its leaf due to the action of specialised hinge cells in the lower epidermis - these cells lose water when water is scarce and lose there turgidity - when water is available they become turgid and open leaves so they can gas exchange for photosynthesis
• The guard cells open and close the stomata, non-turgid cells close the stomata, turgid cells open the stomata
• Marram is not very salt tolerant but maintains a water potential that is lower than other plants - can survive in salty conditions
• The leaves contain many lignified cells that provide support when turgidity is lost keeping the plant upright when water is not available

Question 16

What is a mole?

Answer 16

A borrowing animal that feeds on small animals in the soil

• Marsupial Moles live in Australia and have been evolving separately from placental moles for up to 100 million years
• still share similar characteristics and look very similar

Question 17

What are the characteristics that Placental and Marsupial moles share

Answer 17

• cylindrical body
• small eyes
• strong front legs
• large claws on front legs
• short fur
• short tail
• nose with tough skin fro protection

Question 18

Why do Placental and Marsupial moles look similar

Answer 18

• two unrelated species living in similar habitats evolve to have similar adaptations so therefore look very similar this is called convergent evolution

Question 19

Describe how natural selection works

Answer 19

1. Mutation creates alternative version of a gene
2. this creates genetic variation between the individuals of a species
3. once the variety exists then the environment selects those best adapted- when resources are scare those with the best variations will survive and have an advantage this is the selection pressure
4. the individuals with the best characteristics will survive and reproduce
5. they pass on their genes and the advantageous characteristic to the offspring
6. the next generation will have a high proportion of individuals with the best adapted characteristics, over time the whole population will come to have a variety of the characteristic

Question 20

Describe how some pesticides effect natural selection

Answer 20

An insecticide provides a very strong selection pressure to the insects
- the insects that are not immune to the insecticides will die but those who have some kind of resistance will survive, they can reproduce and pass on their characteristics therefore the resistance will spread rapidly through the population as only those who are resistant survive

Question 21

Give examples of resistant to pesticides

Answer 21

• Pyrethroid insecticides are used to treat mosquito nets, the mosquito malarial parasites developed resistance to pyrethroids as they have produced an enzyme which breaks down the pyrethroid
• DDT is an insecticide which binds to the receptor of the plasma membrane of certain cells in insects - mutations have occurred which has altered the shape of the receptors of the plasma membrane therefore the DDT cannot bind to it

Question 22

Why can insecticides be harmful

Answer 22

insects may be eaten by predators therefore the predators may have a large dose of the insecticide, this means the insecticide can move all the way down the food chain to humans and humans can receive a large dose of it
- DDT has been banned in many areas

Question 23

How have microorganisms become resistant

Answer 23

• before selection there is variety levels of resistance
• variation is caused by mutations that create genetic variation within the species
• after selection the least resistance individuals are killed and the ones that remain are the resistant individuals
• reproduce and pass on the genes and characteristics to the next population
• next population contains a much higher proportion of resistant individuals

Question 24

What leads to antibiotic resistance

Answer 24

• stop taking the antibiotics before you have finished them
• incorrect use of antibiotics
• prescribing multiple antibiotics which reduces the chances that some bacteria will survive

Question 25

Give examples of antibiotic resistance

Answer 25

• MRSA - developed resistance to stronger drugs

Question 26

What is phylogeny?

Answer 26

The study of the evolutionary relationships between organisms

Question 27

What is artificial classification based on?

Answer 27

• based on a few characteristics
• does not reflect any evolutionary relationships
• provide limited information
• is stable

Question 28

Why is artificial classification done?

Answer 28

It is done for convenience - group things in a way that is easy to remember for example all yellow flowers on one page and blue flowers on another

Question 29

What is natural classification

Answer 29

Classification hierarchy

- whole of the living world can be organised into a series of ranked group

Question 30

What does natural classification used …

Answer 30

• uses many characterstics
• reflects evolutionary relationships
• provides a lot of useful information
• may change with advancing knowledge

Question 31

Why is natural classification useful

Answer 31

• reflects real relationships between groups which could be useful, e.g. know of a rare species that we want to find out more about but don’t want to harm it therefore we carry out research on a second species that is very similar to it, this makes conservation more successful

Question 32

Describe an evolutionary tree

Answer 32

we can think of all organisms as belonging to an evolutionary tree, any two species would have had a common ancestor

• when the species started to evolve separately it is show by the branch on a tree
• common ancestor appears at the branch point

Question 33

Common ancestors do not

Answer 33

survive today - we evolved from an ancestor at some point in the past