cell division

Question 1

chromosomes

Answer 1

present in nuclei of all living cells , each is composed of a single DNA molecule . DNA consists of genes , there are chromatin threads and every human has 46 chromosomes and the diploid number is known as 2n and hey exist in 23 homologous pairs which are all similar in shape and size except the sex chromosomes

Question 2

genes

Answer 2

specific sections of DNA , there are 30000 genes in each body cell

Question 3

mitosis

Answer 3

a form of cell division that results in the formation of 2 daughter cells
this is important to ensure each daughter cell has the same number and type chromosomes , method all multicellular organism are formed

Question 4

meiosis

Answer 4

a type of cell division that results in 4 daughter cells and half the number of chromosomes as a parent cell
this is important to ensure the daughter cells have the haploid number and each daughter cell has different combination of genes

Question 5

Variation

Answer 5

refers to differences between individuals
phenotype - actual physical appearance
genotype - genetic make represented by letters

Question 6

genetic variation

Answer 6

controlled by genes and can be passed on by genetics
caused by meiosis , reproduction , mutations eg . albinism and down syndrome

Question 7

environmental variation

Answer 7

caused by different factors in an organisms environment
causes - food, diseases , drugs , climate , education

Question 8

continuous variation

Answer 8

characteristics show continuous graduation from one extreme to another without break

Question 9

discontinuous variation

Answer 9

characteristics show clear cut difference with no break

Question 10

importance of variation

Answer 10

increase chances of survival , most would survive reproduce and pass on genetics to offspring known as natural selection