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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
What is a genetic bottle neck
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
Give 4 reasons why starch is a good energy store
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
What type of glucose makes up cellulose
Beta
28
Name three main features of a chloroplast
The chloroplast envelope The grana made of stacks of thylakoids The stroma
29
How are chloroplasts adapted to the harvesting of sunlight and carrying out photosynthesis
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
What are the functions of a cellulose cell wall
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
Name 4 differences between animal and plant cells
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
Xylem vessels are made of what and transport what
Made of lignin | Transports water & mineral ions
33
What are the 4 requirements for semi conservative replication to take place
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
Explain the process of semi conservative replication
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
What is the first stage of interphase known as
G1
36
What happens in G1
The proteins from which the cell organelles are produced and syntheses
37
What is the second stage of interphase
S1
38
What happens in the S1 stage if the cell cycle
DNA is replicated
39
What is the last stage of interphase
G2
40
What happens during G2 of the cell cycle
Organelles grow and divided and energy stores are increased
41
What is the definition of cell differentiation
Each cell becomes specialised in its structure to suit the role that it will carry out
42
Water loss in insects is reduced how
Waterproof coverings | Small surface area to volume ratio
43
What two ways do gases move in and out of the tracheal system
Diffusion | Ventilation
44
What adaptations does a leaf have that aids gaseous exchange
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
What is ultrafiltration when referring to tissue fluid
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
How does the contents of the lymph keep moving
Hydrostatic pressure from the tissue fluid | Contraction of body muscles that squeezes lymph vessels
47
What is the fine strand of cytoplasm that links adjacent cells called
Plasmodesma
48
The pathway that water moves through the cell wall is known as what
Apoplastic pathway
49
Explain cohesion tension theory
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
Give 3 pieces of evidence that prove cohesion tension
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
Name 4 factors that effect transpiration
Light Temperature Humidity Air movement
52
What are the 5 adaptions of xerophytic plants
``` A thick cuticle Rolling up of leaves Hairy leaves Stomata in pits or groves A reduced surface area to volume ratio ```
53
What is the process of carrying out an immunological comparison
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
Why is courtship behaviour nessary
Recognise members of own species Identify a mate capable of breeding Form a pair bond Synchronise mating
55
What is the process of conjugation in bacteria
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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