Topic 6 inheritance, variation, evolution

Question 1

What is DNA

Answer 1

DNA is a chemical that carries genetic info found in chromosomes in the nucleus.

Question 2

What is a gene

Answer 2

A small section of dna that codes a specific protein

Question 3

What is a genome

Answer 3

Entire set of genetic material/ all the dna in an organism

Question 4

What are dna strands made of

Answer 4

polymers with repeating units called nucleotides

Question 5

What are nucleotides made of

Answer 5

Sugar
a phosphate group
one base ( A, T, C,G)

Question 6

What forms a backbone

Answer 6

sugar and phosphate group form a backbone

Question 7

How do dna bases pair up

Answer 7

A pairs with T
C pairs with G
to form a complementary base

Question 8

What does the order of a base determine

Answer 8

The order of amino acids in a protein

Question 9

What does mRNA

Answer 9

mRNA copies DNA and carries it from the nucleus to the ribosome

Question 10

Why is mRNA needed

Answer 10

As DNA is too big to leave nucleus so mRNA carries it code to the ribosomes

Question 11

What brings amino acid to the ribosomes

Answer 11

Carrier molecules bring the correct amino acids

Question 12

What happens when amino acids are joined together

Answer 12

They fold into specific shapes to allow the protein to perfom

Question 13

What do enzymes do

Answer 13

Enzymes are biological catalyst and they speed up reactions without being used up

Question 14

What do hormones do

Answer 14

Hormones are used to carry messages around the body
eg insulin controls blood sugar levels

Question 15

What are structural proteins

Answer 15

strong proteins that support the body
eg collagen strengths tissues

Question 16

What is mutation

Answer 16

Change in dna sequence of a gene

Question 17

What causes a mutation

Answer 17

Can happen spontaneously or be caused by radiation or chemicals

Question 18

How can a mutation affect a protein?

Answer 18

It can change the sequence of amino acids, changing the protein’s shape and function.

Question 19

What is an insertion mutation?

Answer 19

An extra base is added into the DNA sequence. It can change many amino acids.

Question 20

What is a deletion mutation?

Answer 20

A base is removed from the DNA sequence, which can shift the whole code.

Question 21

What is a substitution mutation?

Answer 21

One base is swapped for another — may change one amino acid or have no effect.

Question 22

What is the difference between sexual and asexual reproduction

Answer 22

Sexual two parents offspring are genetically different
Asexual one parent offspring genetically identical

Question 23

What is meiosis

Question 24

What happens during fertilisation?

Answer 24

A sperm and egg join to form a zygote with a full set of chromosomes.

Question 28

What is a dominant allele?

Answer 28

It is always expressed if present.

Question 29

What is a recessive allele?

Answer 29

It is only expressed if both alleles are recessive.

Question 30

What is a genotype?

Answer 30

The genes an organism has (e.g., Bb or bb).

Question 31

What is a phenotype?

Answer 31

The characteristics shown (e.g., blue eyes).

Question 32

What is cystic fibrosis?

Answer 32

A disorder caused by a recessive gene. It affects lungs and digestion.

Question 33

What is polydactyly?

Answer 33

A disorder caused by a dominant gene. It gives extra fingers or toes.

Question 34

What is variation?

Answer 34

Differences between individuals, caused by genes and environment.

Question 35

What is evolution?

Answer 35

A slow change in species over time due to natural selection.

Question 36

What is natural selection?

Answer 36

Best adapted organisms survive and pass on their genes.

Question 37

What is selective breeding?

Answer 37

Humans choose organisms to breed for useful features.

Question 38

What is genetic engineering?

Answer 38

Changing an organism’s DNA to give it new traits.

Question 39

What are GM crops?

Answer 39

Genetically modified plants that have better yield or resistance.

Question 40

What is cloning?

Answer 40

Making a genetically identical copy of a plant or animal.

Question 41

What is a fossil?

Answer 41

Remains of ancient organisms, giving evidence for evolution.

Question 42

What is antibiotic resistance?

Answer 42

When bacteria evolve to survive antibiotics – evidence of evolution.

Question 43

Who was Gregor Mendel?

Answer 43

Mendel was an Austrian monk who studied inheritance in pea plants in the 1800s.

Question 44

What did Mendel discover?

Answer 44

He found that characteristics are passed from parents to offspring in fixed ratios.

Question 45

What were Mendel’s key ideas?

Answer 45

Inherited units (now called genes) control traits. These units don’t blend — one is dominant, the other recessive.

Question 46

Why wasn’t Mendel’s work recognised at the time?

Answer 46

He didn’t have knowledge of DNA or genes, and his work was published in an obscure journal.

Question 47

What is speciation?

Answer 47

Speciation is the formation of a new species from an existing one.

Question 48

What causes speciation?

Answer 48

Isolation (e.g. by geography) Genetic variation Natural selection Eventually, two groups become so different they can’t interbreed.

Question 49

What is geographic isolation?

Answer 49

When populations are separated by a physical barrier, like a mountain or river.

Question 50

Why can isolated populations become different species?

Answer 50

They adapt to different environments, so over time their genes and traits change.

Question 51

What is classification?

Answer 51

Sorting organisms into groups based on their features and relationships.

Question 52

What is the traditional classification system?

Answer 52

It uses 7 levels: Kingdom, Phylum, Class, Order, Family, Genus, Species

Question 53

Who developed the binomial system?

Answer 53

Carl Linnaeus – he gave each species a 2-part Latin name: genus and species.

Question 54

What are the three domains in modern classification?

Answer 54

• Archaea (primitive bacteria) • Bacteria (true bacteria) • Eukaryota (organisms with complex cells)

Question 55

What is evolutionary tree (phylogenetic tree)?

Answer 55

A diagram showing how organisms are related through evolution.