Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Wills AQA Biology > Module 4 > Flashcards

Module 4 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

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
3
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
4
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
5
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
6
Q

What is Classification?

A

placing organisms into groups

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
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
8
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
9
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
10
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
11
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
12
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
​more common recent ancestor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
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
14
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
15
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
16
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
17
Q

Types of Characteristics?

A

Discontinuous and Continuous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
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
19
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
20
Q

What is Genetic Diversity?

A

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

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

22
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)

23
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]

24
Q

What are the 2 types of selection?

A

stabilising and directional

25
What is stabilising selection?
− 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
26
What is directional selection?
− 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
27
What is a Gene?
− 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)
28
How does a Gene/Exon code for a Protein?
− 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)
29
Properties of triplet code?
− 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
30
How does a mutation lead to a non-functional enzyme?
− 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
31
How is a protein assembled?
− 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) DNA vs RNA? − deoxyribose sugar vs ribose sugar − thymine vs uracil − double stranded vs single stranded − one type vs two types (mRNA and tRNA)
32
What is mRNA?
− messenger RNA − single stranded complementary copy of a gene − carries the code for assembling protein (on DNA called triplet code, on mRNA called ​ codon)
33
What is tRNA?
− 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
34
What is Transciption?
− 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
35
What is Translation?
− 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
36
What does Meiosis produce?
​4 genetically different cells, haploid (half the amount of chromosome/DNA)
37
Benefits of Meiosis? ​
produces gametes which will be used in sexual reproduction in animals & plants ​(2 gametes fuse to form a zygote, zygote develops into organisms)
38
Stages of Meiosis?
Interphase/Meiosis I/Meiosis II/Cytokinesis
39
Interphase? ​
G1: protein synthesis ​S: DNA replication (doubles set of DNA) ​G2: organelle synthesis
40
Meiosis I?
​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)
41
Meiosis II? ​
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)
42
Cytokinesis?
separating cell into 4 (each receives a nucleus and organelles/cytoplasm)
43
How does Meiosis produce Variation?
Crossing Over and Independent Assortment
44
What is crossing over? ​
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
45
What is independent assortment?
​- 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
46
What happens to DNA mass in meiosis?
quarters
47
What happens to Chromosome number in meiosis?
halves (haploid)
48
What is Mutation?
− Change in DNA − 2 types: Chromosome Mutation and Gene Mutation
49
What causes mutation?
random or due to mutagens (e.g. chemicals, radiation)
50
What is a Chromosome Mutation?
− 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
51
What is a Gene Mutation?
− 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

Wills AQA Biology (28 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions