cell cycle

Question 1

describe binary fission in bacteria (3)

Answer 1

1. circular DNA replicates
2. plasmids replicate
3. cytoplasm divides

Question 2

give 3 environmental variables and explain how they increase rate growth

Answer 2

1. increased concentration of glucose means increased respiration
2. increased concentration of oxygen means increased respiration

3.increased temperature means increased enzyme activity

Question 3

describe the behaviour of chromosomes in prophase (2)

Answer 3

1. chromosomes are becoming visible
2. as they are condensing

Question 4

describe behaviour of chromosomes in metaphase (2)

Answer 4

centromeres attach to spindle fibres
chromosomes line up along equator

Question 5

describe behaviour of chromosomes in anaphase (2)

Answer 5

centromeres divide
chromatids pulled to opposite poles of cell

Question 6

describe how meiosis produces haploid cells (4)

Answer 6

1. DNA is replicated
2. there are 2 divisions
3. in first division, homologous chromosomes are separated
4. in second division, sister chromatids are separated
5. produces 4 haploid cells

Question 7

describe viral replication (3)

Answer 7

1. attachment proteins on virus attach to RECEPTORS on host cell
2. nucleic acid enters cell
3. nucleic acid is replicated in cell

Question 8

what is a tumour (2)

Answer 8

• a mass of cells
• uncontrolled mitosis

Question 9

describe how to determine a reliable mitotic index from tissue observed with an optical microscope (3)

Answer 9

• count number of cells in mitosis in field of view
• divide by total number of cells in field of view
• repeat many times

Question 10

what is meant by meristem tissue (1)

Answer 10

Regions of unspecialised cells in plants that are capable of cell division.

Question 11

suggest an advantage and disadvantage of having offspring that are identical to their parents

Answer 11

:) genetic makeup of parent allowed it to survive and reproduce- if offspring has same genetic makeup they will also survive and reproduce

:( genetic variety is limited, if environment changes the species may not have the genes needed to survive in new conditions- become extinct and die

Question 12

describe how viruses are replicated (4)

Answer 12

1. virus attachment proteins attach to cell receptors
2. viral nucleic acid enters cell
3. reverse transcriptase converts viral DNA to mRNA
4. viral protein produced
5. viral components assembled and released from cell