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Biology > Biology 2 > Flashcards

Biology 2 Flashcards

1
Q

How can the effect of chance be minimised

A

Using a large sample size

Analysis of data

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2
Q

Why does genetic variation arise

A

Mutations
Meiosis
Fusion of gametes

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3
Q

What is intraspecific variation

A

Differences between organisms of the same species

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4
Q

What is interspecific variation

A

Differences between organisms of different species

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5
Q

What are the components of DNA

A

Deoxyribose
Phosphate group
Organic/ nitrogenous base

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6
Q

What are the 4 DNA bases

A

Cytosine
Thymine
Adenine
Guanine

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7
Q

Adenine is complimentary to what other base

A

Thymine

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8
Q

What are genes

A

Sections of DNA that contain the coded information for making polypeptides

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9
Q

Sections of DNA that don’t code for proteins are known as what?

A

Introns

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10
Q

What is the point at which two chromatids are joined

A

Centromere

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11
Q

Explain the method can be used to prevent sampling bias?

A

Divide the study area into a grid
Using random numbers generated from a computer obtain a series of coordinates
Take samples at the intersection of each pair of coordinates

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12
Q

What is an allele

A

One of a number of alternative forms of a gene

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13
Q

What is the definition of meiosis

A

Produces four daughter nuclei each with half the number of chromosomes as the parent cell

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14
Q

If a cell has a full set of chromosomes it it’s know as what cell

A

Diploid cell

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15
Q

How many chromosomes are there in a human haploid cell

A

23

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16
Q

Which two way does meiosis bring about variation

A

Independent segregation of homologous chromosomes

Recombination of homologous chromosomes by crossing over

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17
Q

What is the meaning of locus

A

The position of a gene on a chromosome or DNA molecule

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18
Q

What is independent segregation

A

The Random arrangement of homologous chromosomes

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19
Q

What is the process of meiosis

A

Meiosis 1
- the homologous chromosomes pair up and chromatids wrap around each other. This can cause crossing over
- by the end of this stage the homologous pairs have separated with one chromosome from each pair going into one of the two daughter cells
Meiosis 2
- the chromatids move apart
- four cells form with 23 chromosomes each

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20
Q

What is the process of crossing over

A
  • The chromatids of each pair become twisted around one another
  • During this twisting process tensions are created and portions of the chromatids break off
  • These broken portions then rejoin with the chromatids of its homologous partner
  • Usually it is the equivalent portions of homologous chromosomes that are exchanged
  • In this new way genetic combinations are produced
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21
Q

Organisms differ through what?
A) Alleles
B)Genes

A

A

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22
Q

Name 3 factors that effect genetic diversity

A

Selective breeding
The founder effect
Genetic bottlenecks

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23
Q

What is selective breeding

A

It involves identifying individuals with desired characteristics and using them to parent the next generation.
The offspring that don’t exhibit the desired are prevent from breeding
Unwanted alleles are therefore breed out of a population

24
Q

What is the founder effect

A

A few individuals colonise a new region
These individuals will carry a small fraction of the alleles of the population as a whole
The new population develops from the few colonisers so show less genetic variation

25
Q

What is a genetic bottle neck

A

A dramatic drop in numbers of a species occurs this could be a chance event eg. Volcanic eruption
The few survivors will posses much fewer variety of alleles than the original population
When the population becomes re-established the genetic diversity will remain restricted

26
Q

Give 4 reasons why starch is a good energy store

A

It is insoluble therefore doesn’t effect osmosis
Being insoluble means it doesn’t easily diffuse out of cells
It is compact so a lot can be stored in small space
When hydrolysed it forms alpha glucose which is easily transported and readily used in respiration

27
Q

What type of glucose makes up cellulose

A

Beta

28
Q

Name three main features of a chloroplast

A

The chloroplast envelope
The grana made of stacks of thylakoids
The stroma

29
Q

How are chloroplasts adapted to the harvesting of sunlight and carrying out photosynthesis

A

The granal membranes provide a large surface area for the attachment of chlorophyll, electron carriers and enzymes to carry out the first stage of photosynthesis
The fluid of the stroma possesses all the enzymes needed to carry the second stage
Chloroplast contain DNA and ribosomes so they can produce proteins required for photosynthesis

30
Q

What are the functions of a cellulose cell wall

A

To provide mechanical strength to prevent the cell bursting through osmosis
To give mechanical strength to the plant as a whole
To allow water to pass along it to contribute to the movement of water through the plant

31
Q

Name 4 differences between animal and plant cells

A

Cellulose cell wall
Chloroplasts
Normally have a single large vacuole and in a plant if present they are small and scattered throughout the cell
Starch grains are used for storage in a plant and in an animal cell glucose granules are used for storage

32
Q

Xylem vessels are made of what and transport what

A

Made of lignin

Transports water & mineral ions

33
Q

What are the 4 requirements for semi conservative replication to take place

A

The four types of nucleotide
Both DNA strands must act as a template
The enzyme DNA polymerase is needed to catalyse the reaction
A source of chemical energy is require to drive the process

34
Q

Explain the process of semi conservative replication

A

The enzyme DNA helicase breaks the hydrogen bonds linking the DNA base pairs
As a result the double helix separates into two strands and unwinds.
Each exposed polynucleotide strand then acts as a template this attracts the complimentary bases
ATP/ energy is used to activate the nucleotides
The free nucleotides are joined to the DNA strand by DNA polymerase

35
Q

What is the first stage of interphase known as

A

G1

36
Q

What happens in G1

A

The proteins from which the cell organelles are produced and syntheses

37
Q

What is the second stage of interphase

A

S1

38
Q

What happens in the S1 stage if the cell cycle

A

DNA is replicated

39
Q

What is the last stage of interphase

A

G2

40
Q

What happens during G2 of the cell cycle

A

Organelles grow and divided and energy stores are increased

41
Q

What is the definition of cell differentiation

A

Each cell becomes specialised in its structure to suit the role that it will carry out

42
Q

Water loss in insects is reduced how

A

Waterproof coverings

Small surface area to volume ratio

43
Q

What two ways do gases move in and out of the tracheal system

A

Diffusion

Ventilation

44
Q

What adaptations does a leaf have that aids gaseous exchange

A

A thin flat shape provides a large surface area
Many small pores (stomata) in the lower epidermis
Numerous interconnecting air spaces that occur throughout the mesophyll

45
Q

What is ultrafiltration when referring to tissue fluid

A

The filtration under pressure of water and small molecules out of a capillary and the large molecules like cells and proteins staying in the capillaries

46
Q

How does the contents of the lymph keep moving

A

Hydrostatic pressure from the tissue fluid

Contraction of body muscles that squeezes lymph vessels

47
Q

What is the fine strand of cytoplasm that links adjacent cells called

A

Plasmodesma

48
Q

The pathway that water moves through the cell wall is known as what

A

Apoplastic pathway

49
Q

Explain cohesion tension theory

A

Water evaporates from the leaves as a result of transpiration
Water molecules form hydrogen bonds between each other and stick together (cohesion)
Water forms a continuos unbroken pathway across the mesophyll cells and down the xylem
Water evaporates from the mesophyll cells into the air space as a result more water molecules are drawn up due to cohesion
Water is hence pulled up the xylem as a result of transpiration known as the transpiration pull

50
Q

Give 3 pieces of evidence that prove cohesion tension

A

Change in the diameter of a tree trunk according to the rate of transpiration (shrinks during the day due to greater tension)
If the xylem vessel is broken and air enters Walter can no longer be drawn up
When a xylem vessel is broken is doesn’t leek water

51
Q

Name 4 factors that effect transpiration

A

Light
Temperature
Humidity
Air movement

52
Q

What are the 5 adaptions of xerophytic plants

A 
A thick cuticle 
Rolling up of leaves 
Hairy leaves 
Stomata in pits or groves
A reduced surface area to volume ratio
53
Q

What is the process of carrying out an immunological comparison

A

Serum albumin from species A is injected into species B
Species B produces antibodies specific to all the antigen sites on the albumin from species A
Serum is extracted from species B containing antibodies specific to the antigens from species A’s albumin
Serum from species B is mixed with serum of blood of species C
The antibodies respond to the corresponding antigens in species C
This causes the formation of precipitate the more the closer the relation

54
Q

Why is courtship behaviour nessary

A

Recognise members of own species
Identify a mate capable of breeding
Form a pair bond
Synchronise mating

55
Q

What is the process of conjugation in bacteria

A

One cell produces a thin projection tube between the two cells
The donor cell replicates one of its small circular pieces of DNA
This DNA is broken to make it linear before it passes along the tube into the recipient cell
The contact between the cells is brief leaving only time for a portion of the donors DNA to be transferred
In this way the recipient cell inhabits new characteristics

Biology (8 decks)

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