Chromosomes, Mitosis and Binary Fission

Question 1

How do cells become specialised?

Answer 1

Differentiation

Question 2

What is differentiation?

Answer 2

The process by which a cell changes to become specialised for its job
As the cell changes it develops different subcellular structures and turn into different types of cells. This allows them to carry out specific functions

Question 3

When does differentiation occur?

Answer 3

As the organism develops

Question 4

What is the difference in differentiation between animal and plant cells?

Answer 4

Animal cells lose the ability to differentiate whereas plant cells do not

Question 5

What are the cells that differentiate in mature animal cells used for?

Answer 5

Repair and replacing cells

Found in skin or blood

Question 6

What are stem cells?

Answer 6

Undifferentiated cells

Question 7

What is the function of sperm cells?

Answer 7

Reproduction

The function of a sperm is to get the male DNA to the female DNA

Question 8

How are sperm cells specialised for their function?

Answer 8

Long tail and streamlined head to help it swim to the egg
Many mitochondria to provide the cell with energy
Enzymes in the head to digest through the egg membrane

Question 9

What is the function of nerve cells?

Answer 9

Rapid signalling

Question 10

How are nerve cells specialised for their function?

Answer 10

Long cells- cover a large distance

Branched connections at their ends to connect to other nerve cell and form a network throughout the body

Question 11

What is the function of muscle cells?

Answer 11

Contraction

Question 12

How are mucle cells specialised for their function?

Answer 12

Long - lots of space to contract

Contain many mitochondria - energy to contract

Question 13

What is the function of root hair cells?

Answer 13

Absorb water and minerals

Question 14

How are root hair cells specialised for their function?

Answer 14

Long hairs that stick out into the soil - large surface area

Question 15

What is the function of the phloem and xylem?

Answer 15

Transporting substances

Question 16

How are phloem and xylem cells specialised for their function?

Answer 16

Form tubes which transport food and water
Cells are long and join end to end
Xylem cells are hollow in the centre and phloem cells have very few subcellular structures so substances can flow through them

Question 17

Where is the genetic information found in a cell?

Answer 17

Nucleus

Question 18

In what form is the genetic information stored in nucleus

Answer 18

Chromosomes

Question 19

What are chromosomes?

Answer 19

Coiled lengths of DNA molecules

Question 20

What do chromosomes contain?

Answer 20

Genes

Question 21

What is the function of genes?

Answer 21

Control the development of different characteristics eg. hair colour

Question 22

How many copies of each chromosome do body cells normally have?

Answer 22

2

Question 23

How many pairs of chromosomes form a human cell?

Answer 23

23 pairs

Question 24

What is the purpose of the cell cycle/Mitosis?

Answer 24

Growth
Development
Repair

Question 25

What is the name given to the stage in cell cycle where the cell divides?

Answer 25

Mitosis

Question 26

What does the cell cycle result in?

Answer 26

2 new cells identical to the original cell with the same number of chromosomes

Question 27

Describe the first stage of the cell cycle

Answer 27

Growth and DNA replication
In a cell that is not dividing the DNA is spread out in long strings
Before it divides it has to grow and increase the amount of subcellular structures
It then duplicates the DNA (one copy for each new cell) The DNA is copied

Question 28

Describe the duplicated DNA apearance

Answer 28

X shaped chromones where each arm is an exact duplicate of the other

Question 29

Describe the mitosis stage of the cell cylce

Answer 29

The chromosomes line up at the centre of the cell

Cell fibres pull them apart

The two arms of each chromosome go to opposite ends of the cell

Membranes form around each of the sets of chromosomes - these become nuclei of the two new cells

Lastly the cytoplasm and cell membrane divide

The cell has now produced two new daughter cells. They contain the same DNA and are identical to each other and the parent cell

Question 30

How do prokaryotic cells divide?

Answer 30

Binary fission

Question 31

Describe the process of binary fission

Answer 31

The circular DNA and plasmids replicate

The cell gets bigger and the circular DNA strands move to opposite poles of the cell

The cytoplasm begins to divide and the new cell wall form

The cytoplasm divides and 2 daughter cells are produced. Each daughter cell has one copy of the circular DNA but can have variable number of copies of the plasmids

Question 32

Give 2 things that increase the rate of binary fission

Answer 32

Warm environment

Lots of nutrients

Question 33

Give an example of an organism that replicates by binary fission

Answer 33

Ecoli

Question 34

When will an organism replicate?

Answer 34

When conditions are favourable

Question 35

When wont an organism replicate?

Answer 35

When conditions are unfavourable

Question 36

In the right conditions how long does it take ecoli to replicate?

Answer 36

20 mins

Question 37

What is the mean division time?

Answer 37

Average amount of time it takes one bacterial cell to divide in 2