B3d-cell Division Flashcards
Why does multicellular require the development of specialised organ systems?
Communication between cells
Supplying the cells with nutrients
Controlling exchanges with the environment
What are the advantages of being multicellular?
Allows organism to be larger
Allows for cell differentiation
Allows organism to be more complex
Why do multicellular organisms require specialised organ systems?
Communication between cells
Supplying the cells with nutrients
Controlling exchanges with the environment
What is mitosis?
Process that produces new cells for growth and repair
What is mitosis needed for?
Replacement of worn out cells
Repair to damaged tissue
Asexual reproduction
What happens before mitosis?
Dna replicates
What happens to chromosomes jn mitosis?
- Chromosomes line up along centre of cell
- divide as cell fibres pull them apart
- two arms of each chromosome go to opposite poles of one cell
- cytoplasm divides and you get two new cells
Why are sperm cells produced in large numbers?
To increase the chance of fertilisation
What is meiosis?
Type of cell division that creates gametes
What is a diploid?
Two copies of each chromosome
Eg
Body cells
What is a haploid?
Contain one chromosome from each pair
Eg
Gametes
Why does fertilisation result in genetic variation?
Gametes combine to form a diploid zygote
Genes on the chromosome combine to control the characteristics of the zygote
How is the structure of a sperm cell adapted to its function?
Many mitochondria to provide energy
And acrosome that releases enzymes to digest the egg membrane
Why is the chromosome number halved and each cell genetically different in meiosis?
One chromosome from each pair separate to opposite poles of the cell in the first division
Chromosome divide and the copies move to opposite poles of the cell in the second division
