B6: Inheritance, Variation & Evolution

Question 1

What is meiosis?

Answer 1

The process by which gametes are made - genetically different from parent cells

Question 2

How does meiosis work?

Answer 2

-Chromosomes in a diploid cell are copied
-Similar chromosomes pair up and genes swapped between them
-The cell then divided to make 2 diploid cells
-These them divide again to produce 4 haploid cells

Question 3

How do animals and plants reproduce differently?

Answer 3

-Animals mostly reproduce sexually
-Plants can reproduce both sexually (pollen & egg) and asexually

Question 4

How does asexual reproduction happen?

Answer 4

-via MITOSIS
-Daughter cells will be identical

Question 5

What is an advantage of sexual reproduction?

Answer 5

Offspring can become better adapted to the environment that they are in, so they are more likely to survive

Question 6

What is an advantage of asexual reproduction?

Answer 6

-Only one organism is needed to reproduce
-Malaria parasites and some fungi can do both

Question 7

What does the term genome mean?

Answer 7

The entire genetic code in an organism

Question 8

What is DNA?

Answer 8

A double helix polymer that stores genetic code

Question 9

What is a gene?

Answer 9

A portion of DNA that codes for a protein

Question 10

When was the completion of the human genome project and what was it?

Answer 10

-2003
-Scientists mapped out what every gene is responsible for coding
-Helps us identify what genes cause diseases or inherited disorders

Question 11

What is a genotype?

Answer 11

An organism’s specific genetic code

Question 12

What is a phenotype?

Answer 12

How this code is expressed in physical characteristics

Question 13

What are the monomers between 2 strands called and what are they made from?

Answer 13

-Nucleotides
-Made from a sugar and phosphate group
-There are 4 types, A, C, T, G
-Bases: A+T, C+G
-Every three bases code for an amino acid

Question 14

How does protein synthesis work?

Answer 14

-Code is copied by mRNA
-Taken to ribosome which assembles amino acids into polypeptides
-Then proteins (translation) that are then folded into shape
-Mutations can result in wrong proteins being synthesised

Question 15

What are characteristics determined by?

Answer 15

-The type and quantity of proteins synthesised
-Some are controlled by one gene, however most are a result of two or more genes interacting

Question 16

What are alleles?

Answer 16

Different versions of the same gene

Question 17

What are dominant alleles?

Answer 17

Those that result in a characteristic being expressed even if there is another allele present (a recessive allele)

Question 18

Define homozygous

Answer 18

2 of the same allele

Question 19

Define heterozygous

Answer 19

2 different alleles

Question 20

What do we use to predict a certain phenotype?

Answer 20

A punnet square

Question 21

What is polydactyly (extra fingers or toes) caused by?

Answer 21

A dominant allele

Question 22

What is cystic fibrosis caused by?

Answer 22

A recessive allele

Question 23

What causes variation in offspring?

Answer 23

-Genetic factors
-Environmental factors

Question 24

What is Darwin’s Theory of Evolution?

Answer 24

-Random mutations result in variation
-Some organisms are better adapted to their environment
-These compete (‘survival of the fittest’)
-Those better adapted are more likely to survive; over time these desirable characteristics are more pronounced

Question 25

What is Lamarck’s Theory of Evolution?

Answer 25

-Mutations/adaptations are a result of environment affecting characteristics inherited by offspring; not random

Question 26

What is considered to be evidence of Darwinian evolution?

Answer 26

-Antibiotic-resistant bacteria
-If not all bacteria killed, those most resistant will reproduce

Question 27

What determines if organisms are of the same species?

Answer 27

If they can produce fertile offspring

Question 28

What is selective breeding?

Answer 28

Breeding organisms that have desired characteristics to produce offspring in which they are more pronounced

Question 29

What is genetic engineering?

Answer 29

The insertion of a gene into an organism’s genome so it synthesises a specific protein to achieve a desired characteristic

Question 30

What are examples of genetic engineering?

Answer 30

-Insulin-producing bacteria
-Creating GM (Genetically Modified) crops e.g. golden rice which produces Vitamin A
-Disease-resistant crops

Question 31

How does genetic engineering work?

Answer 31

-Desired gene is cut from another organism’s DNA using enzymes
-Gene is inserted into a vector e.g. bacteria, plasmid or virus
-Vector inserts gene into cells of another early in development
-Organism develops with desired characteristic due to every cell synthesising that specific protein

Question 32

What are fossils?

Answer 32

The decayed remains of organisms (or evidence of their existence)

Question 33

What have fossils that look like bones been replaced with?

Answer 33

Minerals

Question 34

What can be left if the conditions for decay are not present?

Answer 34

Soft organic tissue

Question 35

Are footprints that have hardened in mud considered fossils?

Answer 35

Yes, as are other traces of organisms left behind

Question 36

What is cloning?

Answer 36

Producing genetically identical organisms

Question 37

What can you use to clone plants?

Answer 37

-Cuttings
-Tissue cultures

Question 38

What can you use to clone animals?

Answer 38

Cells resulting from fertilisation that can be separated

Question 39

What is the process of cloning a fully grown animal?

Answer 39

-Nucleus taken from skin cell of organism to be cloned
-Nucleus inserted into an egg cell
-Electric shock causes cell to split and development
-Developing cells inserted into surrogate mother

Question 40

What is Linnaeus’s taxonomy?

Answer 40

Classification of organisms
-Kingdom - King
-Phylum - Phillip
-Class - Came
-Order - Over
-Family - For
-Genus - Good
-Species - Soup

Question 41

What is a binomial name?

Answer 41

Genus + Species

Question 42

What 3 things does the domain consist of?

Answer 42

-Archaea (primitive bacteria, extremophiles)
-Bacteria (true bacteria)
-Eukaryota (everything else - DNA contained in nucleus)