meiosis exam qs Flashcards

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1
Q

The student prepared a temporary mount of the onion tissue on a glass slide. She
covered the tissue with a cover slip. She was then given the following instruction.
“Push down hard on the cover slip, but do not push the cover slip sideways.”
Explain why she was given this instruction.

A

Push hard – spread tissue;
Not push sideways – breaking chromosomes

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2
Q

Apart from mutation, explain one other way genetic variation within a species is increased.

A

Random fertilisation;
2. (Produces) new allele combinations

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3
Q

Describe the process of crossing over and explain how it increases genetic diversity.

A

Homologous pairs of chromosomes form a bivalent;
2. Chiasma(ta) form;
3.alleles are exchanged;
4. Producing new combinations of alleles

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4
Q

Explain how the chromosome number is halved during meiosis

A

Homologous chromosomes (pair);
2. One of each (pair) goes to opposite poles

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5
Q

Suggest why the student soaked the root tips in hydrochloric acid in step 2.

A

To separate cell walls;
2. Allowing the stain to pass

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6
Q

Describe how you would determine a reliable mitotic index (MI) from tissue observed
with an optical microscope.

A

Count cells in mitosis in field of view;
2. Divide this by total number of cells in field of
view;
3. Repeat many times

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7
Q

Describe how the process of meiosis results in haploid cells.
Do not include descriptions of how genetic variation is produced in meiosis.

A
  1. DNA replication (during late interphase);
  2. Two divisions;
  3. Separation of homologous chromosomes (in
    first division);
  4. Separation of (sister) chromatids (in second
    division);
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