Past Mock Exam Questions Flashcards
State one function of mitosis in multicellular organisms
1/3
Mitosis is responsible for growth and repair of cells
Mitosis produces new cells
Mitosis is essential to replace old and damaged cells
State one function of meiosis in multicellular organisms
1/2
It allows for sexual reproduction involving gametes while still maintaining the parental chromosome number
It allows for new combinations of genes to be formed which give rise to new variations among organisms
Describe the nucleus at the end of prophase
2/5
Chromosomes become visible as double-stranded structures which are held together by a centromere
These two strands have identical genes
The nucleolus disappears
Spindle fibres appear and form a spindle
The nuclear membrane starts to break down
Explain why the chromosomes begin to move to opposite ends of the cell during anaphase
The chromosomes move apart because the spindle fibres contract resulting in the splitting of the centromere
Name the final stage of mitosis
Telophase
Explain the link between mitosis and cancer
2
Cancer is a group of disorders in which certain cells lose their ability to control both the rate of mitosis and the number of times mitosis takes place
A cell that loses the ability to control its rate of mitosis will result in the formation of a mass of cells called a tumour which can be benign or malignant
State one possible cause of cancer
1/6
Cigarette smoke Asbestos fibres Dioxins Pesticides Ultraviolet radiation Some viruses
Name the two stages of the cell cycle
Interphase
Mitosis (or meiosis)
State any one location in a plant where meiosis occurs
Pollen grain or ovule
Name the phase that occurs before telophase
Anaphase
Describe what happens to the chromosomes during telophase
2
The chromosomes are pulled apart by the contraction of the spindle fibres
One chromosome from each double-stranded chromosome is pulled to opposite poles of the cell
What name is given to the group of disorders that result from the uncontrolled multiplication of cells?
Cancer
Explain what is meant by the term cell continuity
Cell continuity means that all cells develop from pre-existing cells
Name the stage of mitosis during which the chromatin begins to condense
Prophase
What name is given to the part of the cell cycle where no division is taking place?
Interphase
Towards the end of mitosis, in what type of cell does a cleavage furrow form?
Animal
Name the group of disorders that arise if normal regulation of mitosis is lost
Cancer
Where is the equator of a cell?
2
The equator is the middle of the cell
The chromosomes line up across the equator of a cell during metaphase
Explain what is meant by the term diploid
A diploid cell has two sets of chromosomes i.e. it has two of each type of chromosome in the nucleus
In what group of organisms does mitosis normally result in growth
Multicellular
Explain under what circumstances mitosis can result in cancer developing
(2)
When a cell loses it’s ability to control the rate of mitosis
When a cell loses it’s ability to control the number of times mitosis takes place
Give one location where mitosis occurs in flowering plants
Roots
Stem
Anywhere where growth or repair can occur
What is the name given to the stage of mitosis where the chromosomes are lined along the equator?
Metaphase
How would you draw anaphase?
Four spindle fibres are connected to each pole
Each spindle fibre is connected to a chromosome which has just been pulled apart
What role does the spindle fibres have during anaphase?
The spindle fibres contract to split the chromosomes and pull them apart to opposite poles of a cell
What is the diploid number of a cell undergoing metaphase?
4
Distinguish between haploid and diploid
Diploid = A cell with two sets of chromosomes (2n), two of each type of chromosome in the nucleus
Haploid = A cell with one set of chromosomes (n), one of each type of chromosome in the nucleus
