Diversity, Classification and Variation-Topic 4B

Question 1

What does Meiosis involve?

Answer 1

DNA from one generation is passed on to the next by gametes

Question 2

What is a zygote?

Answer 2

When a sperm and egg cell (gametes) join together at fertilisation.

Question 3

Normal body cells have the diploid number (2n) of chromosomes. What does this mean?

Answer 3

Each cell contains two of each chromosome, one from the mum and one from the dad.

Question 4

Gametes have a …… (…) number of chromosomes

Answer 4

Gametes have a haploid (n) number of cells.

half number of chromosomes as diploid cells

Question 5

How is genetic diversity increased within a species?

Answer 5

Fertilisation is random which produces zygotes with different combinations of chromosomes to both parents. (mixing of genetic material)

Question 6

Gametes are formed by…..

Answer 6

Meiosis

Question 7

Where does Meiosis take place?

Answer 7

In the reproductive organs

Question 8

Cells that divide by meiosis are ….. to start with, but the cells that are FORMED from meiosis are …..

Answer 8

Cells that divide by meiosis are diploid to start with but the cells that are formed from meiosis are haploid.

Question 9

What is crossing over?

Answer 9

Homologous pairs of chromosomes pair up and chromatids twist around each other and swap over. They contain the same genes but now different combinations of alleles.

Question 10

Meiosis produces cells that are……..

Answer 10

Meiosis produces cells that are genetically different

Question 11

Name the 2 main events during meiosis that lead to genetic variation

Answer 11

Crossing over of chromatids

Independent segregation of chromosomes

Question 12

What does the crossing over of chromatids in meiosis I mean for the 4 daughter cells.

Answer 12

They contain chromatids with different alleles.

Question 13

What are chromosome mutations caused by?

Answer 13

errors in cell division

Question 14

In humans, if meiosis works properly all four daughter cells should end up with …. ………..

Answer 14

23 chromosomes

Question 15

What is non-disjunction?

Answer 15

a failure of chromosomes to separate properly e.g. non-disjunction of chromosome 21 can lead to Down’s Syndrome.

Question 16

What is Down’s Syndrome caused by?

Answer 16

A person having an extra copy of chromosome 21. Usually one cell gets an extra copy of 21 and another gets none. This means 3 copies of chromosome 21 due to extra copy fusing with another gamete.

Question 17

What do gene mutations involve?

Answer 17

A change in the DNA base sequence of chromosomes

Question 18

Give two examples of gene mutations

Answer 18

Deletion and substitution.

Question 19

How are gametes produced?

Answer 19

Meiosis

Question 20

What is independent segregation?

Answer 20

separating chromosomes into random combinations

Question 21

What is genetic diversity

Answer 21

The number of different alleles of genes in a population.

Question 22

Two organisms belong to the same species if…

Answer 22

they are able to produce fertile offspring

Question 23

How is genetic diversity increased within a population?

Answer 23

Mutations forming new alleles

Different alleles introduced into population

Question 24

Genetic Diversity allows what to occur?

Answer 24

Natural selection

Question 25

Outline how Natural selection increases advantageous alleles in a population

Answer 25

Random mutation = new alleles of gene Some mutations produce beneficial alleles leading to more reproductive success Advantageous allele inherited by next generation Increasing frequency of advantageous allele in the population

Question 26

What type of selection does antibiotic resistance show?

Answer 26

Directional Selection

Question 27

What is Directional Selection?

Answer 27

Where individuals with alleles for characteristics with an extreme type are more likely to survive and reproduce. This could be in response to an environmental change.

Question 28

What is Stabilising Selection?

Answer 28

Where individuals with alleles for characteristics towards the middle range are more likely to survive and reproduce. Occurs when environment ISN'T changing

Question 29

Name some aseptic techniques that should be used when investigating effect of antibiotics on bacterial growth

Answer 29

Disinfect work surfaces, and utensils shouldn't be left on surface. Use sterile equipment and discard safely after use Work near Bunsen flame to draw microbes way from culture Minimise time spent with lid off to reduce airborne microorganisms contaminating the culture.

Question 30

Why are aseptic techniques used?

Answer 30

To prevent contamination as it can affect growth of microorganism or could contaminate with disease causing organisms and get ill.

Question 31

Give the Index of Diversity equation and explain what each part represents

Answer 31

𝐷 = 𝑁(𝑁-1) / Ʃ 𝑛(𝑛-1) N= total number of organisms of all species n=total number of organisms of one species Ʃ = sum of (added together)

Question 32

What does the number calculated by the Index of Diversity mean?

Answer 32

The larger the number the more diverse the area is. | If there is no biodiversity the number Is 1

Question 33

What agricultural practices can reduce biodiversity?

Answer 33

Pesticides, Herbicides, Monoculture (only 1 type of crop which will therefore support fewer organisms) hedgerow removal- reduces hedges and no. of different types, destroying habitats and killing species or forcing to migrate. Woodland clearance= same as hedgerow but with trees

Question 34

Define Biodiversity

Answer 34

Variety of living organisms in an area

Question 35

Define Habitat

Answer 35

Place where an organisms lives

Question 36

What is a community?

Answer 36

All the populations of different species in a habitat

Question 37

How can you know that two organisms belong to the same species?

Answer 37

Two organisms belong to the same species if they are able to produce fertile offspring

Question 38

Courtship behaviour is used to...

Answer 38

attract a mate of the right species

Question 39

Courtship is …… specific

Answer 39

species specific- only members of same species respond to that courtship behaviour, preventing interbreeding and making reproduction more successful. (species recognition.) This specificity allows courtship behaviour to classify organisms.

Question 40

How does a Phylogenetic classification system arrange species?

Answer 40

Based on their evolutionary origins and relationships. Each group called a taxon (plural taxa) (more closely related down the groups)

Question 41

Homo sapiens. Which is the genus and which is the species?

Answer 41

``` Homo = genus (capital letter) sapiens = species ```

Question 42

What advances help to clarify evolutionary relationships between organisms?

Answer 42

immunology and genome sequencing.

Question 43

Genetic diversity within or between species can be made by comparing...

Answer 43

the frequency of measurable or observable characteristics the base sequence of DNA the base sequence of mRNA the amino acid sequence of the proteins encoded by DNA (if share similar aa seq = more closely related)

Question 44

Investigating variation you must make sure results are ….. to do this ….

Answer 44

Random e.g. divide field into grid and use random number generator AND carry out statistical test to make sure sample not due to chance.

Question 45

What does a large standard deviation mean?

Answer 45

That the values in the sample vary a lot.

Question 46

What does a small standard deviation tell you?

Answer 46

That most the sample data = around mean value so varies very little

Question 47

Suggest how a student would obtain data to give a more precise value for the index of diversity of this habitat [2]

Answer 47

- Random sampling e.g. random number generator to know coordinates to place quadrats along grid - Take MORE samples and find a mean

Question 48

fewer species of plant in the oil palm plantation. Lizards feed on plants and insects. Explain why fewer species of plant would lead to fewer species of lizard in the oil palm plantation. [3]

Answer 48

Fewer species of plants = fewer habitats therefore fewer insect species/lower diversity fewer food sources

Question 49

What is species richness?

Answer 49

Number of different species in a community

Question 50

What are some assumptions made with the mark release re-capture method? [2]

Answer 50

Marking doesn't affect survival No immigration (or birth and death rate are equal)

Question 51

What two measurements are needed to calculate an index of diversity? [2]

Answer 51

The total number of individuals of each species | The total number of species

Question 52

Scientists analysed the samples of DNA to find genetic diversity In this investigation, what is meant by genetic diversity? [1]

Answer 52

number of different base sequences found in each gene