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BIOLOGY, M5 2025 HSC 33

The following diagram shows the cell division processes occurring in two related individuals.
 

  1. Compare the cell division processes carried out by cells \(R\) and \(S\) in Individual 1.   (3 marks)
  2. Explain the relationship between Individuals 1 and 2.   (2 marks)
  3. \(A\) and \(B\) are two separate mutations. Analyse how mutations \(A\) and \(B\) affect the genetic information present in cells  \(U\), \(V\), \(W\) and \(X\).   (4 marks)
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a.    Comparison of cell division in cell R vs cell S:

  • Cell R undergoes mitosis, producing two genetically identical daughter cells, whereas cell S undergoes meiosis, producing gametes with half the chromosome number.
  • Mitosis maintains chromosome number, whereas meiosis halves it.
  • Both processes involve DNA replication prior to cell division, doubling the DNA content before division occurs.

b.    Relationship between Individuals 1 and 2

  • Individual 1 is the parent of Individual 2.
  • This is because Individual 1 produces a gamete that contributes genetic information to the zygote that develops into Individual 2.

c.    Mutation’s affect on genetic information

  • Mutation A is a germline mutation, so it is not present in the somatic cells of Individual 1 but could be passed to Individual 2 through an affected gamete.
  • Mutation B is a somatic mutation in Individual 2, so it occurs only in cells descended from the affected somatic cell and cannot be inherited by offspring.
  • Cell U contains neither mutation A nor B.
  • Cell V could contain mutation A, but not mutation B.
  • Cell W could contain both mutations A and B.
  • Cell X could contain mutation A.
Show Worked Solution

a.    Comparison of cell division in cell R vs cell S:

  • Cell R undergoes mitosis, producing two genetically identical daughter cells, whereas cell S undergoes meiosis, producing gametes with half the chromosome number.
  • Mitosis maintains chromosome number, whereas meiosis halves it.
  • Both processes involve DNA replication prior to cell division, doubling the DNA content before division occurs.

b.    Relationship between Individuals 1 and 2

  • Individual 1 is the parent of Individual 2.
  • This is because Individual 1 produces a gamete that contributes genetic information to the zygote that develops into Individual 2.

♦ Mean mark (b) 52%.

c.    Mutation’s affect on genetic information

  • Mutation A is a germline mutation, so it is not present in the somatic cells of Individual 1 but could be passed to Individual 2 through an affected gamete.
  • Mutation B is a somatic mutation in Individual 2, so it occurs only in cells descended from the affected somatic cell and cannot be inherited by offspring.
  • Cell U contains neither mutation A nor B.
  • Cell V could contain mutation A, but not mutation B.
  • Cell W could contain both mutations A and B.
  • Cell X could contain mutation A.

♦ Mean mark (c) 52%.

BIOLOGY, M5 2025 HSC 17 MC

Some phases of cell division in an organism are shown.
  

What is the correct sequence of the process?

  1. \(Q, S, R, T\)
  2. \(Q, R, S, T\)
  3. \(S, T, R, Q\)
  4. \(S, R, T, Q\)
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\(C\)

Show Worked Solution
  • C is correct: The sequence represents meiotic or mitotic division: \(S\) (prophase) → \(T\) (metaphase) → \(R\) (anaphase) → \(Q\) (telophase).

Other Options:

  • A is incorrect: Places \(Q\) (telophase) at the beginning instead of end.
  • B is incorrect: Places \(Q\) (telophase) at the beginning and wrong sequence.
  • D is incorrect: Places \(R\) (anaphase) before \(T\) (metaphase), reversing the actual order.

BIOLOGY, M5 2024 HSC 14 MC

The graph shows the quantity of DNA in one mammalian cell over time.
 

Which of the statements about the cell's activity is correct?

  1. The cell is dividing during section \(O\).
  2. The cell is inactive for the first two hours.
  3. The cell takes one hour to replicate its DNA.
  4. The cell becomes diploid only during section \(N\).
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\(A\)

Show Worked Solution
  • Section \(O\) shows the DNA quantity decreasing sharply, which occurs during cell division (mitosis).
  • At this stage, the parent cell splits into two daughter cells, each receiving half of the DNA content.

\(\Rightarrow A\)

♦ Mean mark 50%.

BIOLOGY, M5 2021 HSC 17 MC

The images show the sequence of changes in the chromosomes (stained black) during mitosis in plant cells.

Which statement is true for mitosis?

  1. Crossing over occurs during prophase.
  2. Sister chromatids separate during anaphase.
  3. Two daughter cells are produced during telophase.
  4. Homologous pairs of chromosomes line up in metaphase.
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`B`

Show Worked Solution
  • Anaphase is the process in which the sister chromatids move away from one another to opposite poles of the spindle and thus separate in mitosis.

`=>B`

♦ Mean mark 45%.

BIOLOGY, M5 2018 HSC 4 MC

Which of the following describes the daughter cells produced as a result of mitosis?

  1. Two genetically different cells
  2. Two genetically identical cells
  3. Four genetically different cells
  4. Four genetically identical cells
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`B`

Show Worked Solution
  • Mitosis is the division of the nucleus which produces two identical sets of DNA, and therefore two identical daughter cells.

`=>B`