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Biology A-level > Definitions > Flashcards

Definitions Flashcards

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1
Q

When is a measurement valid?

A

When it measures what it is supposed to be measuring

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2
Q

What is repeatability?

A

How precise repeated measurements are when when they are taken by the same person using the same equipment under the same conditions

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3
Q

What is reproducibility?

A

How precise repeated measurements are when they are taken by different people using different equipment

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4
Q

What is the uncertainty of a measurement?

A

The interval within which the true value is expected to lie

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5
Q

Define measurement error

A

The difference between a measured value and the true value

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6
Q

What type of error is caused by results varying around the true value in an unpredictable way?

A

Random error

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7
Q

What is a systematic error?

A

A consistent difference between the measured values and the true values

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8
Q

What does zero error mean?

A

A measuring instrument gives a false reading when the true value should be zero

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9
Q

Define a fair test

A

A test in which only the independent variable is changed

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10
Q

what is a null hypothesis?

A

States there is no significant difference between two populations

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11
Q

Continuous variation

A

Data that can take any value on a sliding scale e.g height, mass

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12
Q

Discontinuous variation

A

Data can not be sorted into discrete categories

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13
Q

Interspecific variation

A

Differences between organisms of difference species

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14
Q

Intraspecific variation

A

Differences between organisms of the same species

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15
Q

What is a normal distribution

A

A normal distribution in graphs has a bell shaped curve which is symmetrical (Mean, median and mode are equal)

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16
Q

What is suspension?

A

A mixture in which particles are dispersed throughout the bulk of a fluid.

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17
Q

What does the term Degenerate mean in terms of Genetic code?

A

An amino acid may be specified by more than one type of codon (A set of three adjacent nucleotides in mRNA)

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18
Q

What does the term ‘non-overlapping’ mean in terms of genetic code?

A

Each base in the sequence is read only once

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19
Q

What does the term universal mean in terms of genetic code?

A

Each triplet codes for the same amino acid in all organisms.

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20
Q

Definition of a gene?

A

A sequence of DNA which codes for a polypeptide

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21
Q

Codon

A

Three bases that code for a specific protein.

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22
Q

Introns

A

Left over combinations; do not code for proteins.

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23
Q

Locus

A

A particular position on a particular chromosome where a gene sits.

24
Q

Histone

A

The protein that DNA coils around to fit in a cell. Together these form chromatin (what chromosomes are made of)

25
Q

Alleles

A

Different versions of genes

26
Q

Homologous chromosomes

A

Two chromosomes that carry the same genes but not necessarily the same alleles of the genes.

27
Q

Sister chromatids

A

Two copies of the same chromosomes held together by the centromere.

28
Q

Chromatid

A

One copied section of DNA

29
Q

Apoptosis

A

Cell death

30
Q

Pathogens

A

Disease causing microorganisms

31
Q

Genome

A

Complete set of genes in a cell

32
Q

Proteome

A

Full range of proteins a cell can produce

33
Q

Locus

A

Location of a gene

34
Q

When a genetic code is degenerate

A

More than one triplet codes for the same amino acid.
(This reduces the number of mutations caused by substitution, deletion and insertion)

35
Q

Histones

A

Proteins in eukaryotic cells to form structures called chromosomes.
This is the result of the DNA being tightly compiled around the histones.

36
Q

Introns

A

A segment of a DNA or RNA molecule which does not code for proteins

37
Q

Exons

A

A segment of a DNA or RNA molecule containing information coding for a protein.

38
Q

Polyploidy

A

An individual has three or more sets of chromosomes instead of two

39
Q

Non-disjunction

A

Occurs when chromosomes fail to separate correctly in meiosis
As a result the gametes will have one more or one less chromosome than they should

40
Q

Genetic diversity

A

Total number of different alleles in the population

41
Q

Population

A

Defined as a group of individuals of the same species that live in the same place and are able to breed

42
Q

Niche

A

The species role within the environment

43
Q

Natural selection

A

The process in which fitter individuals who are better adapted to the environment survive and pass on there advantageous genes to future generations by reproduction.

44
Q

Directional selection

A

Occurs when the environmental conditions change and the phenotypes best suited to the new conditions are more likely to survive. As a result these individuals will breed and produce offspring.

45
Q

Stabilising selection

A

The phenotypes with successful characteristics are preserved and those of greater diversity are reduced. This selection does not occur due to changes in the environment. The furthest from the mean are selected against.

46
Q

Anatomical adaptations

A

Physical adaptations either external or internal

47
Q

behavioural adaptationos

A

Changes in behaviour which improve the organisms chance to survive

48
Q

Physiological adaptations

A

Processes inside an organisms body that increases its chance of survival e.g. regulation of blood flow through the skin

49
Q

Diploid

A

A cell with a full set of chromosomes

50
Q

Haploid

A

A cell with no pairs of homologous chromosomes so an odd number of chromosomes

51
Q

Homologous chromosomes

A

Pair of the same chromosome.
Genes are the same but the alleles are different

52
Q

Sister chromatids

A

The copy
(Half old, half new)

53
Q

Species richness

A

Number of different species in a community

54
Q

Genetic bottleneck

A

An event that causes a big reduction in a population and reduces genetic diversity.

55
Q

Founder effect

A

The reduction in genetic diversity that occurs when just a few organisms from a population start a new colony.

Biology A-level (22 decks)

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