Cell Division

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  • Created by: Lily04
  • Created on: 29-05-17 15:44
Describe a unicellular cell and give an example of one.
unicellular: whole body is a single cell, it is microscopic in size, to reproduce the cell just divides to form two new cells (asexual reproduction) e.g. Amoeba
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Explain 3 advantages of a multicellular cell
1.) Can grow large 2.) Cell differentiation (becomes different shapesor sizes to carry out specialised jobs) 3.) organisms become more complex- can develop different organ systems- all the systems work to make up the organism
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How does the body replace lost skin cells?
cell division: when cells divide chromosomes are copied- this means all cells will have the same chromosomes.
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Humans have 23 pairs of chromosomes- what are these pairs called?
homologous pairs
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When a cell has pairs of chromosomes, what is it called?
diploid cell
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What type of cell division makes new cells ?
mitosis
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Why are the new cells made by mitosis genetically identical ?
The DNA (chromosomes) in the nucleus was replicated before the cell divided
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Why do multicellular organisms require specialised organ systems?
To ensure that all their cells get enough nutrients and oxygen, e.g. nervous systems, respiratory systems and transport systems
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Describe mitosis
To copy itself, the DNA unzips to form single strands. New double strands form by complementary base pairing
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Describe meiosis
The cell divides twice to produce four cells with genetically different sets of chromosomes
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What does meiosis produce?
gametes
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Why, in meiosis is the chromosome number halved and why is each cell genetically different?
23 pairs of chromosomes; this is called the diploid number. The gametes contain only one chromosome from each pair. So gametes have half a set of chromosomes, called the haploid number. During fertilisation the gametes join to form a zygote
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Why does fertilisation result in genetic variation?
Reproduction using meiosis results in a lot of genetic variation within a species- offspring have genes from both parents
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Give 2 ways the sperm cell has adapted to its job:
large numbers of mitochondriato release energy for motion; structure called an acrosomeon the sperm head releases enzymes that digest the cell membrane of an egg allowing the sperm inside.
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Card 2

Front

Explain 3 advantages of a multicellular cell

Back

1.) Can grow large 2.) Cell differentiation (becomes different shapesor sizes to carry out specialised jobs) 3.) organisms become more complex- can develop different organ systems- all the systems work to make up the organism

Card 3

Front

How does the body replace lost skin cells?

Back

Preview of the front of card 3

Card 4

Front

Humans have 23 pairs of chromosomes- what are these pairs called?

Back

Preview of the front of card 4

Card 5

Front

When a cell has pairs of chromosomes, what is it called?

Back

Preview of the front of card 5
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