OCR A Level Biology

Topic Questions

2.6 Cell Division, Cell Diversity & Cellular Organisation

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Meiosis produces four unique haploid daughter cells.

At which stage in meiosis are haploid nuclei first formed?

  • Anaphase 2

  •  Telophase 1

  •  Telophase 2

  •  Cytokinesis

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2
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Guard cells are specialised cells in plants which control the opening and closing of stomata on the underside of leaves.

Which of the following is not true about guard cells?

  • They differentiate from stem cells

  • They can carry out mitosis

  • Each guard cell contains the complete organism genome

  • They use ATP even when they are not opening and closing the stomata

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3
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Mitosis and meiosis are both kinds of nuclear division. Mitosis produces two identical, diploid daughter cells and meiosis produces four unique, haploid daughter cells.

Which process below occurs in meiosis but not in mitosis?

  • Crossing over between non-sister chromatids

  • Centrioles produce spindle fibres

  •  Sister chromatids separate and are pulled to either end of the cell

  • New nuclear envelopes form

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4
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Erythrocytes are specialised cells which contain haemoglobin and have a short lifespan.

Which of the following correctly describes how erythrocytes are formed?

  • Erythrocytes undergo mitosis

  • Pluripotent stem cells in the bone marrow produce erythrocyte precursors

  • Multipotent stem cells in the bone marrow produce erythrocyte precursors

  •  Erythrocytes differentiate from other specialised blood cell types

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5
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The cell cycle has three stages, interphase, mitosis and cytokinesis. The mass of DNA in the cell throughout the cell cycle can be measured with flow cytometry. Which of the following stages represents the G2 phase of interphase?

ocr-a-2-6-1e-mcq-q5-dna-mass-graph

  • i

  • ii

  • iii

  • iv

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The cells in the root tip of a Hyacinth plant were viewed under a microscope. The total number of cells in the field of view was 277.

The number of cells at each different stage of the cell cycle are shown below:

Stage of cell cycle Number of cells
Interphase 198
Prophase 36
Metaphase 23
Anaphase 8
Telophase 12

A complete cell cycle in the Hyacinth root tip cells takes 20 hours. Which of the following answers shows the time taken for metaphase to occur?

  • 9 minutes

  • 12 minutes

  • 36 minutes

  • 100 minutes

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2
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Which of the following statements explains how meristems differentiate into xylem and phloem tissue?

  • Stem cells at the inner edge of the cambium differentiate into phloem cells

  • Cambium cells are pluripotent and cell differentiation is stimulated by hormones.

  • Cambium cells that differentiate to form xylem lose their cytoplasm and deposit cellulose into their cell walls

  • Cambium cells that differentiate to form phloem lose their end cell walls.

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3
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Which of the statements below explain why prokaryotic cells do not undergo mitosis?

1 Prophase involves the breaking down of the nuclear envelope.
2 DNA in prokaryotic cells is not replicated.
3 Prokaryotes do not have a nucleus or multiple chromosomes.
  • Statements 1, 2 and 3

  • Statements 1 and 2 only

  • Statements 2 and 3 only.

  • Statement 3 only.

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4
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Many plants are able to asexually produce natural clones, a process that is rare in animals.

Which of the statements below does not explain why plants are more able to form natural reproductive clones?

  • Most animal cells are not totipotent.

  • Plants have meristematic tissue

  • Most plant cells are pluripotent.

  • Plant cells can de-differentiate and then differentiate again.

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5
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A potential future treatment for diabetes is treatment with stem cells to replace faulty pancreatic β cells. A consideration in this is whether stem cells transplanted into the body may lead to the development of cancer.

Which of the statements below does not explain why this is a possibility.

  • An immune response to the transplant may lead to cancerous growth.

  • Formation of tumours may occur as a result of unlimited cell division.

  • Stem cells survive for longer than differentiated cells.

  • Mutation of genes in the cells may occur.

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Which of the following statements, A to D, is not true of human erythrocytes?

  • They are produced from stem cells.

  • They are produced in bone marrow.

  • They are specialised cells.

  • They undergo mitosis.

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2
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Which of the following, A to D, is not true about adult stem cells?

  • They are found in bone marrow.

  • They are not specialised.

  • They are totipotent.

  • They can be used as a renewing source of undifferentiated cells.

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3
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Rheumatoid arthritis is a long-term condition that causes pain, swelling and stiffness in the joints.

Which of the following, A to D, explains why stem cells are a potential source of treatment for rheumatoid arthritis?

  • Stem cells can be harvested from the umbilical cords of newborn babies.

  • Stem cells are cheaper than other drug-based therapies.

  • Stem cells allow regeneration of a variety of tissue types.

  • Stem cells can be obtained from embryos without any ethical concerns.

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The image below shows a micrograph of two different types of blood cell.

blood-smear

Which of the following rows, A to D, shows the correct cell names from the image above?

  P Q
A neutrophil erythrocyte
B erythrocyte epithelial cell
C erythrocyte neutrophil
D epithelial cell erythrocyte

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5
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Which of the following statements, A to D, correctly explains why meristems can differentiate into xylem vessels in plant stems?

  • Meristems are living and unspecialised.

  • Meristems are living and specialised.

  • Xylem vessels are dead and specialised.

  • Xylem vessels are dead and unspecialised.

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6
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Meiosis is an important feature of sexual reproduction.

Which of the following processes occurs during meiosis and contributes to genetic variation in the offspring?

1   crossing over
2   gene mutation
3   random fertilisation 

  • 1, 2 and 3

  • only 1 and 2

  • only 2 and 3

  • only 1

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7
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Corals are a group of animals that usually live on the sea bed close to the surface of the water.

Many corals can reproduce both sexually and asexually.

Which of the following statements about asexually-produced coral offspring is not true?

  • All offspring produced from an individual organism will be genetically identical.

  • If a change in the environment harms one of the offspring produced from an individual organism it will probably harm them all.

  • Meiosis occurred in order to produce the offspring.

  • The offspring will tend to thrive if conditions are similar to those present when the parent organism reproduced.

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During cell division, the chromosome number in the cells changes.

The following sequences describe the chromosome number in cells before, during and after different types of cell division.

q5-paper-1-june-2017-ocr-a-level-biology

Which of the options, A to D, correctly describes the stages of mitosis and meiosis in human cells?

  • 1 is mitosis, 2 is meiosis

  • 2 is mitosis, 3 is meiosis

  • 3 is mitosis, 4 is meiosis

  • 4 is mitosis, 1 is meiosis

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9
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The haploid chromosome number in the koala, Phascolarctos cinereus, is 8.

Independent assortment of chromosomes in meiosis contributes to genetic variation in the gametes of the koala.

How many genetically different versions of koala gamete would it be possible for one individual to produce if independent assortment were the only source of genetic variation?

  • 64

  • 128

  • 256

  • 512

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Which statement explains the significance of mitosis in the development of whole organisms?

  • Mitosis can be controlled at certain points in development, which will change body plans.

  • Sex cells are produced by mitosis, which allows new organisms to be produced.

  • Mitosis limits the total number of cells in an organism, which will change its shape.

  • Budding in yeast is an example of mitosis, producing new multicellular organisms.

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