3.4 Genetic information, variation and relationships between organisms Flashcards

Question

What is a chromosomal mutation? (1 point)

Answer 1

Changes in the structure or number of whole chromosomes

Answer 2

Polyploidy – occurs when organisms have 3 or more sets of chromosomes and occurs mainly in plants Non-disjunction – Chromosomes fail to separate during meiosis

Answer 3

Mitosis produces cells for growth and repair whereas meiosis leads to production of gametes and ensures diversity in reproduction Mitosis involves 1 cell division whereas meiosis involves 2 Mitosis produces 2 daughter cells whereas meiosis produces 4 In mitosis the daughter cells are diploid (two copies of every chromosome) whereas in meiosis the cells are haploid (only one copy of each) In mitosis the daughter cells are identical to parent cells whereas in meiosis there is more variation as not identical

Answer 4

The process by which a diploid nucleus (2n) divides to produce four haploid daughter nuclei (n)

Answer 5

Interphase - DNA unravels and replicates so there are two copies of each chromosome (chromatids) Prophase 1 - Nuclear envelope breaks down and chromosomes condense Metaphase 1 - Spindle fibres form and chromosomes line up along the equator Anaphase 1 - Homologous chromosomes are pulled apart to opposite poles Telophase 1 and cytokinesis - Two daughter cells are formed and cytoplasm divides Prophase 2 - Two diploid daughter cells are produced, and nuclear envelope does not need to break down again Metaphase 2 - Chromosomes line up along equator and attach to spindle fibres Anaphase 2 - Sister chromatids are pulled apart to opposite poles Telophase 2 and cytokinesis - Nuclear envelope reforms and four haploid cells are produced

Answer 6

Crossing over of chromatids – Crossing over of chromatids in meiosis 1 means that each of four daughter cells formed from meiosis contains chromosomes with different alleles Independent segregation – Each homologous pair of chromosomes in cells is made up of one maternal chromosome and one paternal chromosome. When homologous pairs are separated in meiosis 1 its random which chromosome from each pair ends up in which daughter cell. So, four daughter cells produced have completely different combinations of maternal and paternal chromosomes which leads to genetic variation in offspring

Answer 7

The total number of different alleles in a population

Answer 8

Greater number of different alleles of a species, the greater the genetic diversity. The greater the genetic diversity, the more likely the species can adapt to environmental change which leads to natural selection

Answer 9

Mutations in the DNA which forms new alleles Gene Flow - different alleles being introduced into a population when individuals from another population migrate into them and reproduce

Answer 10

The differential survival and reproduction of individuals due to differences in their phenotype

Answer 11

A mutation occurs creating a new allele Individuals that have an advantageous allele that increases their chance of survival are more likely to survive, reproduce and pass on the beneficial allele This means greater proportion of next generation inherits beneficial allele So, they are more likely to survive, reproduce and pass on their genes The new allele increases in frequency in the population

Answer 12

1. Anatomical – appearance e.g. shorter ears and thicker fur in Arctic foxes 2. Physiological – chemical reactions/processes internally e.g. oxidizing of fat rather than carbohydrates to produce extra water for camels 3. Behavioural – Actions of the organism e.g. migration of swallows from UK to Africa to escape cold in winter

Answer 13

An observable physical characteristic that organisms have

Answer 14

Genetic make-up of an organism

Answer 15

Total number of alleles in a population at a specific time

Answer 16

The number of times an allele occurs within the gene pool - % of all chromosomes in a population that carry that allele

Answer 17

The process by which organisms that are better adapted to their environment tend to survive and breed at the expense of those less well adapted

Answer 18

Directional selection | Stabilising selection

Answer 19

Where individuals with alleles for characteristics of an extreme type are more likely to survive and reproduce Mutations result in increased genetic diversity Change in the environment occurs Selection favours individuals that vary in one direction from the mean The mean characteristic of the population changes Phenotypes of one extreme in the population is selected for

Answer 20

Where individuals with alleles for characteristics towards middle of range are more likely to survive and reproduce Mean phenotype is favoured Extreme phenotypes are selected against Environment is stable Number of individuals with that trait increases

Answer 21

Directional selection selects extreme phenotype whereas stabilising selects mean Directional changes the characteristics of the population whereas stabilising preserves them Directional makes curve keep same shape but shifts mean to left or right whereas stabilising curve becomes narrower and higher, but mean doesn’t change

Answer 22

A set of behaviours in which an animal attempts to attract a mate and exhibit their desire to copulate e.g. vocalizations, displays of beauty or strength, ritualised movements (dances)

Answer 23

``` Male communicates a courtship signal This acts as visual stimulus to females Females nervous system detects and if receptive responds to stimulus with a specific innate of her own This acts as stimulus to male The male responds ```

Answer 24

1. Enables members to recognise their own species to prevent crossbreeding/infertile offspring 2. Allows animal to identify a mate that is capable of breeding 3. Helps form pair bonds to lead to successful breeding and raising of offspring 4. Helps synchronise mating seasons to ensure maximum chance of fertilisation

Answer 25

The organisation of living organisms into groups

Answer 26

The theory and practice of biological classification

Answer 27

Artificial classification | Phylogenetic classification

Answer 28

Based on analogous characteristics (characteristics that have the same function but not same evolutionary origin) Not based on evolutionary relationships E.g. colour of flowers, size, having wings

Answer 29

Classifies species based on shared features derived from ancestors Based on evolutionary relationships between organism and ancestor Partly based on homologous characteristics Arranges groups of organisms into a hierarchy

Answer 30

``` Life Domain Kingdom King Phylum Phillip Class Came Order Over Family From Genus Great Species Spain ```

Answer 31

Broadest at top and most specific at bottom Smaller groups within larger groups No overlap Each group is called a taxon (taxa) Based on their ancestry/evolutionary relationship

Answer 32

A group of similar organisms able to reproduce to give fertile offspring

Answer 33

First name comes from the Genus (upper case first letter) | Second name comes from the Species (lower case)

Answer 34

Domain is the highest taxonomic rank - Bacteria - Eukarya - Archaea

Answer 35

Single celled prokaryotes with following features: - No membrane bound organelles - Unicellular (some cells may occur in chains or clusters) - Cell walls made of murein - Single loop of naked DNA made up of nucleic acids but not associated with histones - Smaller ribosomes 70s - Some may cause disease - Important decomposers in environment as breaks down dead organisms

Answer 36

- Membrane bound organelle such as nucleus - Not all possess cells with cell walls e.g. animals - If cell walls present, made of cellulose - Ribosomes are larger 80s - DNA is associated with proteins - Split into 4 kingdoms: Protoctista, fungi, plantae, animalia

Answer 37

- Single celled prokaryotes - Similar shape and size to bacteria - Genes and protein synthesis similar to eukaryotes - No murein in cell walls - More complex form of RNA polymerase for transcription and translation

Answer 38

Most recent representatives at end of branches | Oldest ancestor species at base of tree

Answer 39

Observable characteristics – changes in evolutionary features must have been mirrored by changes in proteins and therefore DNA

Answer 40

+ Easier as anyone can do it + Cheaper as does not require and advanced equipment + Easier to observe - Patterns of inheritance not always clear - Differences are often discrete so interpretation subjective - If using fossil data, it might be hard to find - Most genes are polygenic - May be a result of similar environments not similar evolutionary history

Answer 41

Can get more accurate definition of a species by comparing: 1. DNA base sequences/mRNA sequences - comparing the exact order of nucleotides on the DNA to determine how diverse organisms are or spot where mutation and therefore new species occurred - mRNA is complementary to DNA - BUT, can cost a lot and take a while to complete 2. Amino acid sequence in proteins - Determined by the DNA or mRNA - Similarity of amino acid sequence = similarity of species - BUT, can cost a lot, take a while to complete and some DNA will be non-coding/non functional

Answer 42

Heat both organism A and B to separate strands of DNA by breaking hydrogen bonds Combine single strands of DNA from both organisms Cool to allow renaturation of double-stranded DNA (hydrogen bonds reform) Determine degree of hybridisation (Complete hybridisation = all bonds form between strands so organisms identical) (Partial hybridisation = Some bonds reform but others don’t so organisms are related) (No hybridisation = No bonds formed so organisms are unrelated)

Answer 43

Increase temperature again Record temperature required to separate two strands Higher temp required = greater number of hydrogen bonds formed = greater similarity in DNA = Closer related species are

Answer 44

Serum containing human antigens is injected into another species (usually rabbits as easier to keep in lab) Rabbits immune system makes anti-human antibodies which are collected Antihuman antibodies are mixed with serum from other species The more similar the species is to the human, the more antibody-antigen complexes formed Precipitate forms when antibody-antigen complexes are formed. The more precipitate, the closer the evolutionary relationship

Answer 45

The number of different species AND the number of individuals of each species within any one community

Answer 46

The variety of genes possessed by the individuals that make up any one species

Answer 47

The range of different habitats within a particular area

Answer 48

Species Richness – Number of different species in a particular area at one time PROBLEM: Doesn’t consider number of individuals of each species

Answer 49

N(N-1) d= sum of n(n-1) ``` d= species diversity N= total number of organisms of all species n= total number of organisms of each species = sum of ```

Answer 50

Agriculture (demand for food has more than doubled) Used land for home and industry Deforestation Production of fossil fuels These factors have had direct impact on species diversity, genetic diversity, ecosystem diversity and therefore the whole food web

Answer 51

Monoculture (growing only one species) - Reduction in species and genetic diversity both directly and indirectly Lack of intercropping (rotating what is grown each season) - Drains the soil of its nutrients which results in monoculture Competition for space - Natural species/habitats cannot grow as are outcompeted Use of pesticides and fertilisers - Kills species as can be toxic and enter water cycle causing eutrophication Cattle - Overgrazing and trampling causes a reduction in species diversity and habitats Draining wetland and marshes - Removes nutrients and moisture from soil so species cannot grow Removing hedgerows - Destroys habitats and food sources

Answer 52

Deforestation is the permanent clearing of forests and the conservation of land for other uses such as agriculture, grazing or settlement Leads to a loss of species, reduction in habitats, reduction in food sources, reduction in decay so soil nutrients decrease and reduction in species diversity index

Answer 53

A reduction in biodiversity can directly affect the phenotypic and genetic variation present Two types of variation that may result: - Intraspecific (variation WITHIN a species) - Interspecific (variation BETWEEN species)

Answer 54

Quadrats Transects When using these methods, they cannot take a single measurement as may be unreliable, unrepresentative and not trustworthy

Answer 55

Choices made by investigator are biased and sample unrepresentative deliberately or unwillingly Avoided by using random sampling

Answer 56

Even if bias is avoided, sample may be unrepresentative as all individuals are the same Avoided using data analysis and increasing sample size

Answer 57

Determines the extent to which chance may have influenced the data by measuring how far the data deviates from the mean The closer to the mean the values are, the more probable we can be that our results are correct A measure of the width of the curve on a normal distribution curve Indicates the range of values either side of the mean The distance from the mean until the curve changes from convex to concave

Answer 58

1. Calculate mean 2. Subtract mean from each of individual values 3. Square the values (ensure no negatives) 4. Add all squared numbers together 5. Add number of values and minus 1 6. Sqare root some of square values divided by number of values minus 1