Cells + Biological molecules - Exam Questions

Question 1

Describe the role of spindle fibres and the behaviour of the chromosomes during prophase.

Answer 1

Chromosomes condense.

Question 2

Describe the role of spindle fibres and the behaviour of the chromosomes during metaphase.

Answer 2

Centromeres attach to spindle fibres and chromatids line up along the equator of the cell.

Question 3

Describe the role of spindle fibres and the behaviour of the chromosomes during anaphase.

Answer 3

The centromeres divide, chromatids pulled to opposite poles and the spindle fibres contract.

Question 4

Why is not as much detail as an electron microscope shown on an light microscope?

Answer 4

Light has longer wavelength so lower resolution.

Question 5

Name an organelle found in both a chloroplast and a prokaryotic cell.

Answer 5

70S ribosomes

Question 6

Why does the solution that cells are held in cell fractionation need to be buffered?

Answer 6

It reduces the effect of pH activity so the organelles would not be denatured.

Question 7

Describe how a peptide bond between two amino acids to form a dipeptide.

Answer 7

Condensation between amine group of one amino acid and the carboxyl group of another amino acid.

Question 8

The secondary structure of a polypeptide is produced by bonds between amino acids. Describe how.

Answer 8

Hydrogen bonds between amine group and carboxyl group

Question 9

Two proteins have the same number and type of amino acids but different tertiary structures. Explain why.

Answer 9

Different primary structure/ sequence of amino acids so forms hydrogen, ionic and disulfide bonds in different places.

Question 10

Describe the difference in the structure of starch and cellulose.

Answer 10

Starch is formed from alpha glucose and cellulose is formed from beta glucose.
The position of hydrogen and hydroxyl groups inverted in alternating glucoses.

Question 11

Explain one way in which starch molecules are adapted for their function in plant cells.

Answer 11

Insoluble - doesn’t affect water potential
OR
Large molecule - can’t leave cell
OR
Helical - compact

Question 12

Explain how cellulose molecules are adapted for their function in plant cells.

Answer 12

Long and straight chains become linked together by many hydrogen bonds to form fibrils so provides strength to cell wal.

Question 13

Describe the difference in structure between phospholipids and triglycerides.

Answer 13

In a phospholipid, one fatty acid is replaced by a phosphate group.

Question 14

Describe how you may test foods to see if fats are present.

Answer 14

Add ethanol, then add water.
A white emulsion shows that lipids are present.