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OCR A-level Biology > Classification > Flashcards

Classification Flashcards

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1
Q

Why do we classify organisms

A

For convenience

To make studying similar organisms easier

See relationships between organisms

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2
Q

What are the 8 taxonomic classes

A 
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
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3
Q

What is the binomial system

A

A way of naming an organism

Consists of the Genus and species

E.d Homo Sapiens

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4
Q

What is the biological definition of a species

A

A group of organisms that can feely interbreed to produce fertile offspring

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5
Q

Why is the traditional taxonomic classification of 2 kingdoms not always accurate

A

because everything was grouped into plants or animals

somethings don’t fit in

Ergot fungus doesn’t move and has root like structurers (like a plant) but doesn’t photosynthesise and digests nutrients like an animal

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6
Q

What are the 5 new kingdoms in the taxonomic system

A

Prokaryotae

Protoctista

Fungi

Plantae

Animalia

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7
Q

What is Convergent evolution and how could it make observable feature classification inaccurate

A

Animals adapt and evolve to suit their environment

2 species could be completely unrelated but live in the same environment meaning they may have developed certain similar physical or behavioural traits.

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8
Q

How can biological molecules be used to determine phylogenic relationships

A

If we assume that early life all had the same biological molecule makeup then changes must be down to evolution

2 species with more similarities are more closely related

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9
Q

What is Cytochrome c

A

A protein that is used in respiration, so all living organisms that respire have it.

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10
Q

How is Cytochrome c used to find relationships between 2 species

A

Not all Cytochrome c molecules are the same

You can map the amino acid sequence of 2 organisms’ Cytochrome c protein and compare the differences

The more similarities the closer they are related

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11
Q

What is artificial classification

A

It is where you classify things only based on a few characteristics

Doesn’t reflect evolutionary relationships

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12
Q

What is Natural Classification

A

Involves a detailed study of the individuals you are trying to classify

Works in more detail

For example dog breeds look very different but biologically are very similar so are part of the same species

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13
Q

What was the name of Darwin’s mechanism that explained Evolution

A

Natural Selection

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14
Q

What is Darwin’s principle of ‘Survival of the Fittest’

A

It is a struggle to survive

Better adapted individuals have more chance of survival

They pass on these traits to their offspring

Over time many changes may lead to a nee species

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15
Q

How can DNA be used to prove evolutionary relationships

A

If you map the base sequences in the DNA

More similarities in the sequences mean that the individuals will have more common traits

It also means that there have been less mutations and thus the species only diverged relatively recently

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16
Q

Define intraspecific variation

A

Variation within a species

17
Q

Define interspecific variation

A

Variation that occurs between species

18
Q

What is the relationship between genetic diversity of a species and level of intraspecific variation

A

The greater the genetic diversity the greater the intraspecific variation

19
Q

What is continuous variation

A

Where the data is a spectrum

There are 2 extremes and a full range of data between that

A vast majority are around the mean of the data

E.g Human height, length of leaves on an oak tree

20
Q

Why is the number of individuals at the extremes of continuous variation small

A

Because traits that are represented by continuous variation are often controlled by more than 1 gene

21
Q

What is discontinuous variation

A

Where there are 2 or more distinct categories with no intermediate values

Usually regulated by 1 gene

E.g. eye colour, gender, human blood groups

22
Q

What is genetic variation

A

Variation in genes that we inherit off our parents

No 2 individuals are the same

Variations that we can’t control

However we share many genes with others in our species as well as other species

23
Q

What is environmental variation

A

Characteristics that are caused by environment

Such as if you eat more you will weigh more, or if you spend time in the sun then your skin will tan and get darker

24
Q

What is adaption?

A

Any variation that helps an organism to survive

25
Q

What are the 3 types of adaptions?

A

Anatomical
Behavioural
Physiological

26
Q

What are anatomical adaptions?

A

Any structural changes to an organism that help it survive

27
Q

What are Behavioural adaptions?

A

A specific behaviour that helps an organism to survive

28
Q

What are Physiological adaptions?

A

An adaptions that ensures the correct functioning of cell processes

29
Q

Give examples of anatomical adaptions in marram grass

A

Long roots - reach more water

Wide spread roots - get more water when it rains

Curled leaves - reduces water loss by maintaining gradient

Lower epidermis has hair - reduces water loss

Low stomata density - reduces water loss

Thick waxy cuticle - reduces evaporation from cells

30
Q

Give a behavioural adaption of marram grass

A

When water stress is high it rolls its leaf tighter and closes stomata

This maintains a low water potential outside the leaf which reduces water loss by transpiration

31
Q

Give physiological adaptions of marram grass

A

Leaf can roll more or less due to specialised hinge cells in the lower epidermis

Guard cells can open and close stomata more easily

It maintains a lower water water potential than other plants allowing it to survive in salty conditions

Leaves have lignified cells that provide support when turgidity is lost

32
Q

What is the name given to the process whereby 2 unrelated species share similar characteristics due to their environment?

A

Convergent Evolution

33
Q

Outline the process of natural selection

A

Mutation creates alternate allele

Creates genetic intraspecific variation

This mutation may give a the species an advantage in their environment

If that is the case they are more likely to survive and are therefore more likely to pass this allele on

Over generations this allele will become more frequent in the population

OCR A-level Biology (24 decks)

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