Science Human Bio

Question 1

Define cell division

Answer 1

All cells come from pre-existing cells through two methods:
Mitosis ( somatic cell)
Meiosis ( gametes)

Question 2

What is Mitosis involved in

Answer 2

• growth
• repairment
• tissue repair
• asexual reproduction

Question 3

What is the chromosome structure?

Answer 3

When DNA replicates, chromosomes become visible as X’s

1 chromosome has 2 chromatids

Question 4

Draw interphase and what is it

Answer 4

Normal cell function
DNA begins to replicate
Cell is diploid

Question 5

Order of the main steps of mitosis

Answer 5

Intaphase 
Prophase 
Metaphase 
Anaphase 
Telophase 
Cytokinesis

Question 6

What is prophase and draw it

Answer 6

Chromosomes become visible
Nuclear membrane breaks down
Spindle fibres begin to from from centrioles
Chromosomes line up along equator
Spindle fibres attach to centromere of each chromosome

Question 7

What is anaphase and draw it

Answer 7

Spindle fibres contract and pull chromatids apart

Chromatids seperate to opposite sides of the cell

Question 8

Telophase what is it and draw it

Answer 8

• chromosomes arrive at the poles of the cell
• nuclear membrane begins to reform
• cellular membrane begins to brake down

Question 9

What is cytokinesis and draw it

Answer 9

• cell divides into two separate cells

- daughter cells are both diploid (2n) and have identical information in them

Question 10

How is mitosis difference to miosis

Answer 10

Mitosis: Take place in the somatic cells of the body
Meiosis: Take place in the germ cells.

Mitosis: The cell divide only once.
Meiosis: There are two cell divisions, the first and the second meiotic divisions.

Question 11

What’s meiosis

Answer 11

• The nuclear division that prevents the doubling of chromosomes at fertilisation
• results in haploid cells
• requires 2 seperate divisions to have the chromosome

Question 12

Variations- crossing over

Answer 12

During the 1st division when all chromosomes align at the equator, sections of chromatids can mix

Contributes to making us all different

Question 13

What is fertilisation

Answer 13

Occurs when haploid gametes from two parents fuse together to form a diploid zygote

Question 14

What is variation

Answer 14

• The particular sperm that fertilises the egg does so by chance
• many possible sperm- many possible genetic combinations
• another source of variation

Question 15

What is fertilisation

Answer 15

Occurs when haploid Ganges from two parents fuse together to form a diploid zygote

Question 16

What is growth

Answer 16

• zygote contains 23 chromosomes from farther and 23 from mother
• zygote divides rapidly via mitosis to form an embryo
• mitosis occurs over & over again until grown

Question 17

Female and male

Answer 17

• 1 sex chromosome and 22 pairs of autos ones
• female: XX
• male: XY

Question 18

How do we get twins

Answer 18

Identical- cell divides and two embryoyes develop

Non identical- two eggs are released and fertilised by two different sperm