Brainscape's Knowledge GenomeTM

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


See full index

AS AQA Biology > Section 4 > Flashcards

Section 4 Flashcards

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

What is Biodiversity?

A

 variety in an ecosystem

 variety of habitats and variety of species

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

What is Species Diversity?

A

 number of different species

 number of individuals for each species

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

What is Genetic Diversity?

A

 variety of alleles in a species population

 the larger number of individuals in a species, the larger the genetic diversity

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

Benefit of high species diversity?

A

 Stable ecosystem
 each species is less likely to become extinct (due to high genetic diversity)
 & if a species does become extinct it will not affect the food chain as there are other species available

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

How to measure Species Diversity for an area?

A

 Species Diversity Index
 takes into account the number of different species and how many individuals there are for each species
 the larger the species diversity index, the larger the species diversity

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

How does deforestation lower species diversity?

A 
	(deforestation is the removal of trees for wood & space)
	decreases plant species diversity
	less variety of habitats
	less variety of food sources
	decreases animal species diversity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How does agriculture/farming lower species diversity?

A

 deforestation to make space for farm
 only grow a few plants & keep a few animal species
 selectively breed plants & animals
 use pesticides to kill other species

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

What is Classification?

A

placing organisms into groups

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

What is Hierarchical Classification?

A

 large groups divided into smaller groups with no overlap

 domain, kingdom, phylum, class, order, family, genus, species

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

What is Binomial Naming System?

A

 using Genus name and Species name to name organism
 Genus name first in capital, Species name second in lower case
 e.g. tiger = Felix tigris

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

What is a Species?

A

a group of individuals with similar characteristics that can interbreed to produce fertile offspring

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

Why are the offspring from 2 different species mating infertile?

A

 offspring will have a odd number of chromosomes
 therefore, cannot perform meiosis, cannot produce gametes
 example: horse + donkey = mule,
mule is infertile,
horse has 64 chromosomes/donkey has 62 chromosomes,
horse gamete has 32 chromosomes/donkey gamete has 31 chromosomes,
therefore, mule has 63 chromosomes

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

What is Phylogenetic Classification?

A

based on evolutionary relationships – how closely related different species are and how recent a common ancestor they have

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

3 ways of comparing relationship between different species?

A

DNA Hybridisation: comparing DNA base sequence

	- take DNA from 2 species to be compared
	- radioactively label one of the DNA
	- heat both sets so double strand separates
	- cool so single strands join together
	- look for Hybrid DNA (one strand from species A, one strand from species B)
	- identify Hybrid DNA by 50% radioactivity
	- heat Hybrid DNA to measure similarity
				results      =	higher temperature required
						more hydrogen bonds present
						more complementary base pairing
						more similar the base sequence
						more similar the species
						more closely related
						more recent a common ancestor

AA Sequence: comparing AA sequence for the same protein (e.g. haemoglobin in mammals)

				results     = 	more similar the AA sequence
						more similar the DNA base sequence
						more similar the species
						more closely related
						more recent a common ancestor
(comparing DNA sequence better then comparing AA sequence: 
DNA sequence provides information on INTRONS and triplet code is DEGENERATE)

Protein Shape: comparing shape of the same protein (e.g. albumin) using immunological technique

		- comparing species A and species B
		- take albumin from species A
		- place in a blood of rabbit
		- rabbit will make antibodies against albumin of species A
		- takes these antibodies and place in blood from species B
		- if the albumin in species B has a similar shape to species A,
			the antibodies will bind to form antigen-antibody complexes,
			this will then form a precipitate
				results     = 	more precipitate
						more complexes
						more similar shape
						more similar the species
						more closely related
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is Variation?

A

difference in characteristics between organisms

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

Types of Variation?

A

intraspecific = differences between organisms of the same species
interspecific = differences between organisms of different species

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

Causes of Intraspecific Variation?

A

Genetic Factors = same genes but different alleles (allele are different type/forms of genes)

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

Causes of Interspecific Variation?

A

Genetic Factors = different genes and different alleles

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

Types of Characteristics?

A

Discontinuous and Continuous

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

Properties of Discontinuous Characteristics?

A

characteristics fall into certain groups with no overlap (e.g. blood group) – determined by genetics only (a single gene)

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

Properties of Continuous Characteristics?

A

characteristics show a range (e.g. height) – determined by genetics (a few genes, polygenes) and environment

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

What is Genetic Diversity?

A

genetic variation, the variety of alleles within a population of a species

23
Q

Benefit of high genetic diversity?

A

species able to adapt with changes in the environment e.g. if a new disease arises, some individuals will have characteristics to survive, and will reproduce passing on their alleles, so the species does not become extinct

24
Q

What can lower genetic diversity?

A

small population size (e.g. founder effect – where the numbers start low, or genetic bottleneck – where the numbers decrease)

25
Q

What is natural selection and adaptation?

A

 variation in population of species
(genetic diversity/genetic variation/variety in gene pool)
 new alleles arise by random mutation
 environment applies a selection pressure on the population
 those with favourable characteristics/favourable alleles/selection advantage/better adapted survive, the others die [natural selection]
 the ones that survive will reproduce, passing on their favourable alleles
 if this happens for many generations, then that characteristic will become most common – the allele will become more frequent [adaptation]

26
Q

What are the 2 types of selection?

A

stabilising and directional

27
Q

What is stabilising selection?

A

 when the environment favours those with the most common characteristic – those on the extreme dies out
 the common characteristic increases in proportion
 the range (standard deviation) will reduce

28
Q

What is directional selection?

A

 when the environment favours those individuals with characteristics on one of the extremes
 over time this will become the most common characteristic
 normal distribution will shift to that extreme

29
Q

What is a Gene?

A

 a section of DNA that codes for a protein
 made out of intron and exon
 intron = non-coding DNA (function e.g. turns gene on or off)
 exon = coding DNA (codes for protein)

30
Q

How does a Gene/Exon code for a Protein?

A

 made out of a sequence of bases
 each 3 bases code for 1 amino acid (called triplet code)
 therefore,
 sequence of bases
 determines sequence of triplet codes
 which determine the sequence of AAs
 = polypeptide chain/primary structure (folds to secondary, then to tertiary/quaternary)

31
Q

Properties of triplet code?

A

 degenerate = each AA has more than one triplet code
 non-overlapping = each base is read only once
 stop codes = occur at end of sequence – do not code for an AA

32
Q

How does a mutation lead to a non-functional enzyme?

A

 change in base sequence
 change in sequence of triplet codes
 change in sequence of AAs
 change in primary structure
 change in hydrogen/ionic/disulfide bonds
 change in tertiary structure (3D shape)
 change in active site shape
 substrate no longer complementary
 can no longer form enzyme-substrate complex

33
Q

How is a protein assembled?

A

 by transcription and translation
 transcription = production of a single stranded complementary copy of a gene (called mRNA)
 translation = use sequence of codons on mRNA to assemble protein (tRNA brings in AAs)

34
Q

DNA vs RNA?

A

 deoxyribose sugar vs ribose sugar
 thymine vs uracil
 double stranded vs single stranded
 one type vs two types (mRNA and tRNA)

35
Q

What is mRNA?

A

 messenger RNA
 single stranded complementary copy of a gene
 carries the code for assembling protein (on DNA called triplet code, on mRNA called codon)

36
Q

What is tRNA?

A

 transfer RNA
 single stranded RNA folded over into a ‘clover leaf’ shape (held by hydrogen bonds between the bases)
 has an AA attachment site on the top
 has 3 specific bases on the bottom (anticodon)
 anticodon binds to complementary codons on mRNA

37
Q

What is Transciption?

A

 occurs in nucleolus of nucleus
 producing a single stranded complementary copy of a gene (called mRNA)
 DNA is double stranded, 1 strand called coding strand & 1 strand called template strand, the template strand will be used to build mRNA
 process,
 DNA Helicase breaks the hydrogen bonds between complementary bases in the gene
 the double strand of the gene unwinds
 leaves 2 separate strands (1 coding strand and 1 template strand)
 complementary RNA nucleotides bind to exposed bases on the template strand
 RNA Polymerase joins the sugar-phosphate backbone of the RNA strand
 leaves pre-mRNA (contains introns and exons)
 the copies of the introns are removed by splicing
 leaves mRNA

38
Q

What is Translation?

A

 takes place on ribosomes of Rough Endoplasmic Reticulum
 uses the sequence of codons on the mRNA to assemble the protein (tRNA brings in AAs)
 process,
 mRNA leaves nucleus via nuclear pore
 mRNA attaches to a ribosome
 complementary tRNA carrying specific AAs bind to the codons on mRNA via their anticodon
 the AAs on the tRNA are joined by peptide bonds

39
Q

What does Meiosis produce?

A

4 genetically different cells, haploid (half the amount of chromosome/DNA)

40
Q

Benefits of Meiosis?

A

produces gametes which will be used in sexual reproduction in animals & plants
(2 gametes fuse to form a zygote, zygote develops into organisms)

41
Q

Stages of Meiosis?

A

Interphase/Meiosis I/Meiosis II/Cytokinesis

42
Q

Interphase?

A

G1: protein synthesis
S: DNA replication (doubles set of DNA)
G2: organelle synthesis

43
Q

Meiosis I?

A

Prophase I: DNA coils to form chromosomes, nucleus breaksdown, spindle fibres form, crossing over occurs
Metaphase I: homologous pair of chromosomes line up in middle of cell and attach to spindle fibre via centromere
Anaphase I: spindle fibres pull, homologous pair of chromosomes separate to opposite sides by independent assortment
Telophase I: chromosomes uncoil, nucleus reforms (left with 2 nuclei)

44
Q

Meiosis II?

A

Prophase II: DNA coils to form chromosomes, nucleus breaksdown, spindle fibres form
Metaphase II: chromosomes line up in middle of cell and attach to spindle fibre via centromere
Anaphase II: spindle fibres pull, centromere splits, sister chromatids move to opposite sides by independent assortment
Telophase II: chromatids uncoil, nucleus reforms (left with 4 genetically different nuclei)

45
Q

Cytokinesis?

A

separating cell into 4 (each receives a nucleus and organelles/cytoplasm)

46
Q

How does Meiosis produce Variation?

A

Crossing Over and Independent Assortment

47
Q

What is crossing over?

A

occurs in Prophase I of Meiosis I
homologous pairs of chromosomes wrap around each other and swap equivalent sections of chromatids – produces new combination of alleles

48
Q

What is independent assortment?

A
  • in Anaphase I of Meiosis I – the homologous pairs of chromosomes separate
    • in Anaphase II of Meiosis II – the chromatids separate
    • independent assortment produces a mix of alleles from paternal and maternal chromosomes in gamete
49
Q

What happens to DNA mass in meiosis?

A

quarters

50
Q

What happens to Chromosome number in meiosis?

A

halves (haploid)

51
Q

What is Mutation?

A

 Change in DNA

 2 types: Chromosome Mutation and Gene Mutation

52
Q

What causes mutation?

A

random or due to mutagens (e.g. chemicals, radiation)

53
Q

What is a Chromosome Mutation?

A

 In plants, inherit more than one diploid set of chromosomes – called polyploidy
 In animals, homologous pair of chromosome do not separate in meiosis, so either inherit one extra or one less chromosome – called non-disjunction

54
Q

What is a Gene Mutation?

A

 a change in the base sequence of DNA
 2 types = substitution and insertion/deletion
 substitution = replace one base for another, changes one triplet code
can be silent (new triplet code codes for same AA), mis-sense (codes for a different AA, so protein shape changes slightly), non-sense (codes for a stop codon, so polypeptide chain not produced)
 insertion = adding a base, deletion = removing a base
both insertion/deletion causes frameshift, all the triplet codes after the mutation changes, so normal polypeptide chain/protein not produced

AS AQA Biology (4 decks)

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