GCSE Biology – Genetic crosses

Last updated: 30/04/2020
OCR 21st Century GCSE Science – Biology foundation You and your genes GCSE Biology – Genetic crosses

Learning Objectives

-I can explain how characteristics can be controlled by genes
-I can predict the results of a genetic cross by completing a Punnett square diagram

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  1. Current
  2. Review
  3. Answered

  1. What is phenotype?

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  2. How many pairs of chromosomes do human cells contain?

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  3. How are sex chromosomes determined?

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  4. What are the two sex chromosomes?

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  5. Which sex chromosome is the larger one?

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  6. Which sex chromosome is the smaller one?

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  7. What do females have as their sex chromosomes?

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  8. What do males have as their sex chromosomes?

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  9. Where do baby boys inherit their Y chromosome from?

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  10. Where do baby boys inherit their Y chromosome from?

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  11. What does homozygous mean?

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  12. What does heterozygous mean?

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  13. What does homologous chromosomes mean?

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  14. How many of our chromosome pairs are homologous?

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  15. What is a dominant allele?

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  16. What is a recessive allele?

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  17. What do we give the dominant gene in a gene pair?

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  18. What do we give the recessive gene in a gene pair?

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  19. Describe the gene pair Hh.

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  20. Describe the gene pair dd.

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  21. Describe the gene pair AA.

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  22. Which pair is not homologous?

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  23. What is a Punnett square?

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  24. If two parents are heterozygous for a gene, what is the probability of the offspring having homozygous dominant genes?

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  25. If two parents are heterozygous for a gene, what is the probability of the offspring having heterozygous genes?

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