Rosie Week 3

Question 1

Explain the steps to meiosis .

Answer 1

• copies of genetic material are made
• pairs of chromosomes are pulled to each end of the cell
• the cell divides twice to form 4 gametes
• each gamete has a single set of chromosomes
• all gametes are genetically different

Question 2

What are the advantages of sexual reproduction?

Answer 2

• more time and energy efficient as they do not need to find a mate
• faster than sexual reproduction
• can produce many identical offspring when conditions are favourable

Question 3

How does malaria reproduce in the human host?

Answer 3

Malaria reproduce asexually in the human host

Question 4

How does malaria reproduce in the mosquito?

Answer 4

Malaria reproduces sexually in the mosquito

Question 5

What is the structure of DNA?

Answer 5

A double helix

Question 6

Define a gene.

Answer 6

A small section of DNA, which codes for a particular protein

Question 8

Define a genome.

Answer 8

The entire genetic material of an organism

Question 9

What is the name of the polymer that makes up dna?

Answer 9

Nucleotides

Question 10

What are the 3 components of a nucleotide?

Answer 10

Common sugar, a phosphate group, and a base

Question 11

What do 3 bases code for?

Answer 11

An amino acid

Question 12

What are the 4 bases?

Answer 12

A, T, C, G

Question 13

What are the pairs of bases?

Answer 13

A and T

C and G

Question 14

Explain the steps in the transcription stage of protein synthesis.

Answer 14

• the two strands of DNA are pulled apart
• the mRNA nucleotides match to their complementary base and join to form a chain
• the mRNA passes out of the nucleus to the cytoplasm

Question 15

Explain the steps in the translation stage of protein synthesis.

Answer 15

• the mRNA attaches to a ribosome
• amino acid’s are brought to the ribosome by carrier molecules
• the ribosome reads the triplets of bases on the mRNA and joins the amino acids in the correct order
  -once the protein chain is complete it folds into the correct shape

Question 16

What are the types of dna mutations?

Answer 16

• a base is inserted into the code
• a base is deleted from the code
• a base is substituted

Question 17

How do mutations affect the protein?

Answer 17

A change in the sequence of bases may alter the shape of the protein and may jeopardise its ability to perform its function

Most mutations do not alter the protein

Question 18

Explain the process of evolution.

Answer 18

• there is variation in the population
• individuals with the phenotype more suited to the environment are more likely to survive and successfully breed
• this process happens over many generations

Question 19

What is the definition of selective breeding?

Answer 19

The process by which humans breed plants and animals to have particular genetic characteristics

Question 20

What are the issues with selective breeding?

Answer 20

• it can lead to inbreeding which increases the risk of disease
• it reduces variation in a population which makes a species more susceptible to extinction

Question 21

Define genetic engineering

Answer 21

Genetic engineering involves modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic

Question 22

Describe the process of genetic engineering

Answer 22

• Enzymes are used to isolate the desired gene
• this gene is then inserted into a vector
• The vector is used to insert the gene into the required cells
• The genes are transferred into the cells an early stage in their development so that they develop with the desired characteristic

Question 23

What is a tissue culture?

Answer 23

A small group of cells from part of a plant that will grow into an identical new plant

Question 24

How can cloning be useful?

Answer 24

Cloning can be used to preserve a rare plant species

Question 25

What is the process of cloning an adult cell?

Answer 25

- The nucleus is removed from an unfertilised egg - the nucleus from an adult body cell is inserted into the egg cell - an electric shock stimulates the egg to divide to form an embryo - the embryo contains the same genetic information as the adult skin cell - when the embryo has developed into a bowl of cells it is inserted into the womb of an adult female

Question 26

Why were Charles Darwin’s views not initially accepted?

Answer 26

- It’s challenged the idea that God made all living animals - there was insufficient evidence at the time to convince many scientists - the mechanism of inheritance and variation was not understood until 50 years after his work was published

Question 27

What are the methods by which fossils may be formed?

Answer 27

- from parts of organisms that have not decayed because oxygen or moisture were absent - when parts of the organism are replaced by minerals as they decay - as preserved traces of organisms such as footprints

Question 28

Why is it difficult for fossils to tell us how life started on earth?

Answer 28

- most early life forms were softbodied and therefore left very few traces - any traces that may have been left have been destroyed by geological activity

Question 29

What are the factors that may contribute to extinction?

Answer 29

- changes in the environment which species cannot adapt fast enough to - new predators - a new disease - destruction of a habitat - new competition from other animals that have more advantageous features

Question 30

What can we do to prevent the development of antibiotic resistant bacteria?

Answer 30

- doctors should not prescribe antibiotics to treat non-serious infection infections - patients should complete their course of antibiotics so all the bacteria is killed and non-survive to mutate - the agricultural use of antibiotics should be restricted

Question 31

What is archaea?

Answer 31

Primitive bacteria that live in extreme environments

Question 32

When did Darwin believe life started on earth?

Answer 32

3 billion years ago