Checkpoint task

Genes, inheritance and selection

Instructions and answers for teachers

These instructions cover the learner activity section which can be found on page 5. This

Checkpoint Task should be used in conjunction with the KS3–4 Gateway Science Biology A

Transition Guide Genes, inheritance and selection, which supports OCR GCSE (9–1) Gateway

Science Biology A.

When distributing the activity section to the learners either as a printed copy or as a Word file you will need to remove the teacher instructions section.

IntroductionLearners should work through these questions to assess their prior understanding of the KS3

content. The questions are scaffolded to assist them and of increasing difficulty.

This checkpoint task will hopefully separate out the learners that are ‘just saying the right words’

from those that truly understand the concept. As can be seen from the specification there are three

assessment objectives being tested. AO1 demonstrating knowledge and understanding, AO2 apply

knowledge and understanding and AO3 analysing information and ideas. Simple recall of a

scientific fact is not sufficient and so students need to be introduced to the ‘apply’ and ‘analyse’

strands.

Teacher preparationQuestions in this activity can be asked in the form of a worksheet or a visual display. If using a

worksheet the question should be cut and pasted into an appropriate word processing package

and printed. Alternatively the questions could be projected by PowerPoint – one question per slide.

The answers can also be projected up for peer review/self-marking.

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Answers Answers shown in red

Task 11. Draw a diagram of a human cell.

2. On your cell, label where you might find the chromosomes by adding a ©.

3. How many are there in a normal human cell?

4. What are chromosomes made up of?

5. Draw a sketch of the material that chromosomes are made from.

6. Draw a diagram of a chromosome.

7. Are all chromosomes the same?

8. Where do we get our chromosomes from?

9. Describe the purpose of chromosomes.

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(Standard items to be included at this level are cell membrane nucleus and cytoplasm)

Nucleus should be clearly identified.

23 pairs or 46 chromosomes.

DNA

Standard double helix drawing.

Standard X shape chromosome drawing here although allow a single line to represent a pre-replicated DNA strand.

No, each pair of chromosome carries different genes and pair 23 can be different (XX for females and XY for males).

Parents sperm and egg cells.

They carry information for everything from our enzymes to our hair colour and personality traits.

10. Suggest what you think would happen if a chromosomes was missing from a fertilized egg.

11. If your mother had blonde hair, and your dad had brown hair, can you work out what your chances of having blonde hair would be.

Blonde is recessive so mother must be bb, father could be heterozygous (Bb) or homozygous (BB).

If homozygous,

Father

B B

Mother b Bb Bb

b Bb Bb

Therefore all children will be brown haired.

If father is heterozygous,

Father

B b

Mother b Bb bb

b Bb bb

Approximately 50% of the children could be blonde

12. What is a species? Can two different species breed together to have babies?

13. Sometimes within a species an individual is produced that is slightly different from all the

others. If this difference makes that individual it better adapted to its environment. How can

this contribute to the development of the species?

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The cell cannot survive and so typically dies. There are some exceptions to this but not at this level.

A group of organisms which share similar traits and are capable of breeding together. Two different species can sometimes breed together successfully but the result is a hybrid which is usually infertile.

That the organism has a better chance of surviving and passing on its genes (including the advantageous trait) to the next generation which in turn may have inherited it. This is the basis of evolution by natural selection.

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Checkpoint learner activity

Task 11. Draw a diagram of a human cell.

2. On your cell, label where you might find the chromosomes by adding a ‘C’.

3. How many are there in a normal human cell?

4. What are chromosomes made up of?

Version 1 5 © OCR 2016

5. Draw a sketch of the material that chromosomes are made from.

6. Draw a diagram of a chromosome.

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7. Are all chromosomes the same?

8. Where do we get our chromosomes from?

9. Describe the purpose of chromosomes.

10. Suggest what you think would happen if a chromosomes was missing from a fertilized egg.

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11. If your mother had blonde hair, and your dad had brown hair, can you work out what your chances of having blonde hair would be.

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12. What is a species? Can two different species breed together to have babies?

13. Sometimes within a species an individual is produced that is slightly different from all the

others. If this difference makes that individual it better adapted to its environment. How

can this contribute to the development of the species?

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