Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology Revision > Genetics, Biodiversity and Classification (Topic 4) > Flashcards

Genetics, Biodiversity and Classification (Topic 4) Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What are the three components of
nucleotides?

A

A pentose sugar, a phosphate group, an
organic base.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Describe the structure of DNA.

A

Made up of a deoxyribose sugar, a
phosphate group, and one of four
organic bases (A,C,G,T). It is
double-stranded, and hydrogen bonds
between the bases form a helix shape.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe the role of DNA.

A

Carries genetic information, determines
our inherited characteristics.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe the structure of RNA.

A

Made up of a ribose sugar, a phosphate
group, and one of four organic bases
(A,C,G,U). It is single stranded.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe the role of RNA.

A

Transfers genetic information from DNA
to ribosomes for protein synthesis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Which bases are purine and which are
pyrimidine?

A

Purine (double ring) = adenine, guanine.
Pyrimidine (single ring) = cytosine,
thymine, uracil.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How is DNA in eukaryotic cells different
from in prokaryotic cells?

A

• Eukaryotic cells= found in nucleus, long and
linear. Associated with histone proteins to form
chromosomes. Mitochondria and chloroplasts
contain prokaryotic-like DNA.
• Prokaryotic cells= short and circular. Not
associated with proteins.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the genetic code?

A

The order of bases on DNA. Consists of
codons (triplets of bases that code for a
particular amino acid).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Identify features of the genetic code.

A

• Non-overlapping= each triplet is only read once.
• Degenerate= more than one triplet codes for the
same amino acid (64 possible triplets for 20
amino acids).
• Universal= same bases and sequences used by
all species.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is a gene?

A

A sequence of bases on a DNA molecule
that codes for a specific sequence of
amino acids to make a polypeptide. Can
also code for functional RNA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is a locus?

A

The fixed position on a DNA molecule
occupied by a gene.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is an allele?

A

Different versions of the same gene,
found at the same locus on a
chromosome.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are exons and introns?

A

Exons= regions of DNA that code for
amino acid sequences. Separated by
one or more introns.
Introns= regions of DNA that do not code
for anything.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Where are introns found?

A

between exons
within genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the genome?

A

The complete set of genetic information
contained in the cells of an organism.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the proteome?

A

The complete set of proteins that can be
produced by a cell.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Describe the structure of messenger
RNA (mRNA).

A

A long, single strand. Its base sequence
is complementary to the DNA it was
transcribed from.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Suggest advantages of using mRNA
rather than DNA for translation.

A

• shorter & contains uracil = breaks down
quickly so no excess polypeptide forms
• single-stranded & linear = ribosome moves
along strand & tRNA binds to exposed bases
• contains no introns

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe the structure of transfer RNA
(tRNA).

A

A single strand of around 80 nucleotides
that is folded over into a clover leaf
shape. On one end is an anti-codon, on
the opposite end is an amino acid
binding site.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is produced by transcription?

A

mRNA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Where does transcription take place?

A

In the nucleus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Outline the process of transcription.

A

• DNA uncoils into two strands with
exposed bases. One used as a template.
• Free nucleotides line up next to their
complementary bases, and are joined
together by RNA polymerase.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What happens to mRNA after
transcription?

A

In eukaryotic cells, pre-mRNA must be
spliced to remove introns, leaving only
the coding regions. Then it moves out of
the nucleus and attaches to a ribosome.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is produced by translation?

A

Proteins.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Where does translation take place?

A

In the cytoplasm (or you can say in the ribosomes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Outline the process of translation.

A

• The anti-codon of tRNA attaches to
complementary bases on the mRNA.
• Amino acids bonded to tRNA form peptide
bonds, continuing to form a polypeptide
chain until a stop codon is reached.
• This process requires ATP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is a mutation?

A

An alteration to the DNA base sequence.
Often arise spontaneously during DNA
replication.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Why might a mutation not lead to
change in the amino acid sequence?

A

• Genetic code is degenerate so
mutation may end up coding for same
amino acid as the original triplet.
• Mutation may occur in intron.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is a substitution mutation?

A

When a nucleotide in the DNA sequence
is replaced by another. This is more
likely to be a quiet mutation, meaning no
change occurs in the amino acid
sequence.

30
Q

What is a deletion mutation?

A

When a nucleotide in the DNA sequence
is lost. This is more likely to be harmful
and significant, as it leads to a frame
shift which means the entire amino acid
sequence will be different.

31
Q

What is a mutagenic agent? Give
examples of this.

A

Factors that increase the rate of gene
mutation. X-rays, UV light, gamma rays,
certain chemicals e.g. in alcohol and
tobacco.

32
Q

What is a polyploidy chromosome
mutation?

A

Where an individual has three or more
sets of chromosomes instead of two.

33
Q

What is chromosome non-disjunction?

A

When chromosomes fail to separate
correctly in meiosis, resulting in gametes
with one more or less chromosome than
normal.

34
Q

What is meiosis?

A

A form of cell division that produces four
genetically different haploid cells (cells
with half the number of chromosomes
found in the parent cell) known as
gametes.

35
Q

How does meiosis differ from mitosis?

A

• Meiosis produces four genetically different
cells with half the number of chromosomes
as the parent cells.
• Mitosis produces two genetically identical
cells with the same number of
chromosomes as the parent cells.

36
Q

What happens during meiosis Ⅰ?

A
  1. Homologous chromosomes pair to form bivalents.
  2. Crossing over (exchange of sections of genetic
    material) occurs at chiasmata.
  3. Cell divides into two. Homologous chromosomes
    separate randomly. Each cell contains either
    maternal or paternal copy.
37
Q

What happens during meiosis Ⅱ?

A
  1. Independent segregation of sister
    chromatids.
  2. Each cell divides again, producing 4
    haploid cells.
38
Q

In which two ways does meiosis produce
genetic variation?

A
  1. Crossing over during meiosis Ⅰ
  2. Independent assortment (random
    segregation) of homologous
    chromosomes & sister chromatids
    Result in new combinations of alleles
39
Q

Define population.

A

All the organisms of a particular species
that live in the same place, at the same time.

40
Q

Define genetic diversity.

A

The total number of different alleles in a
population.

41
Q

What advantage does a high genetic
diversity provide?

A

Ability to adapt to a change in
environment; allows natural selection to
occur.

42
Q

Explain how natural selection results in
development of new characteristics.

A

• Random mutations result in new alleles.
• Some alleles provide an advantage, making an
individual more likely to survive and reproduce.
• Their offspring receive the new allele, and
frequency continues to increase over many
generations.

43
Q

What is directional selection?

A

Occurs when environmental conditions
change. Individuals with phenotypes suited to
the new conditions will survive and pass on
their genes. Over time the mean of the
population will move towards these
characteristics.

44
Q

Give an example of directional selection.

A

Antibiotic resistance. Bacteria with a mutation
allowing them to survive in the presence of
antibiotics will reproduce. Therefore frequency
of this allele will increase and the population
will shift to have greater antibiotic resistance.

45
Q

What is stabilising selection?

A

Occurs when environmental conditions
stay the same. Individuals closest to the
mean are favoured, and any new
characteristics are selected against.
Results in low diversity.

46
Q

Give an example of stabilising selection.

A

Birth weight; babies that weigh around
3kg are more likely to survive than those
at lower or higher weights.

47
Q

Define a niche.

A

The role of a species within its
environment. Species sharing the same
niche will compete with each other.

48
Q

What are the three types of adaptation?
Give examples of each.

A

• Anatomical (changes to body structure) e.g. oily
fur.
• Physiological (changes to bodily processes) e.g.
venom production.
• Behavioural (changes to actions) e.g. hibernation.

49
Q

Define species.

A

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

50
Q

What are the advantages of courtship
behaviour?

A

Individuals can recognise sexually
mature members of their own species of
the opposite sex, synchronise mating,
form a pair bond, and successfully
breed.

51
Q

Define classification.

A

The process of arranging organisms into
groups.

52
Q

Name the eight groups in the
classification hierarchy, from largest to
smallest.

A

domain → kingdom → phylum → class
→ order → family → genus → species

53
Q

What system is used to give species a
universal name?

A

Binomial naming system.

54
Q

What are the two components to a
binomial name?

A

Generic name= the genus the organism
belongs to. Two closely related species
will share the same genus.
Specific name= the species the organism
belongs to.

55
Q

How are binomial names handwritten?

A

The first letter of the generic name
should be capitalised, with the rest in
lowercase. The whole name should be
underlined.

56
Q

What is phylogenetic classification?

A

The process of arranging organisms into
groups based on their evolutionary
origins and relationships.

57
Q

How can we clarify evolutionary
relationships between organisms?

A

Analyse their molecular differences.
Advances in immunology/genome
sequencing provide clear pictures of how
related two organisms are.

58
Q

Explain hierarchical classification.

A

• groups within groups
• no overlap between groups

59
Q

What is biodiversity?

A

The variety of living organisms. It can be
measured in terms of species diversity
(number of species in a community),
ecosystem diversity (range of different
habitats) and genetic diversity.

60
Q

Define community.

A

All the different species that live in one
area and interact with each other.

61
Q

How do you calculate index of
diversity (d)?

A

d = (N(N-1))
/
(Σn(n-1))
N= total number of
organisms of all species.
n= total number of organisms of each species.
Σ = sum of.

62
Q

What impact does agriculture (farming)
have on species diversity?

A

decreases species richness
• farmland is typically used for only 1
species (monoculture)
• use of pesticides/ herbicides

63
Q

What impact does agriculture (farming)
have on genetic diversity?

A

decreases
• farmers select for certain
characteristics, which reduces number
of different alleles in the population

64
Q

How can biodiversity be increased in
areas of agriculture?

A
  1. Use hedgerows instead of fences.
  2. Grow different crops in the same area,
    or rotate crops around after a season.
  3. Limit use of pesticides and herbicides.
65
Q

Name four ways we can measure
genetic diversity.

A
  1. Frequency of observable characteristics.
  2. Base sequence of DNA.
  3. Base sequence of mRNA.
  4. Amino acid sequence.
66
Q

What is meant by gene technology?

A

Sampling DNA or mRNA in order to read and
compare the base sequence of organisms.
Alternatively the amino acid sequence can be
studied as this will also provide information on
the organism’s mRNA and DNA sequences.

67
Q

Why do scientists prefer to use gene
technology instead of observation?

A

Simply inferring DNA differences by observing
an organism’s characteristics is not reliable;
the characteristics could be coded for by more
than one gene, or could be influenced by the
environment.

68
Q

What is meant by interspecific and
intraspecific variation?

A

Interspecific= differences between
individuals of different species.
Intraspecific= differences between
individuals of the same species.

69
Q

What is sampling?

A

Selecting a group of individuals to
measure that will represent the whole
target population.

70
Q

How can a random sample be achieved?

A

Create a grid for your sample area, and
then randomly generate coordinates
where a quadrat or transect can be
placed. Repeat until required sample
size is reached.

Biology Revision (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions