Biology: Genetics and Cell Biology: cram pack

haemophilia is X-linked recessive (allele h). A carrier mother, X^HX^h, has children with an unaffected father, X^HY. The mother's gametes run down the side. Click the cell for an unaffected son.

1. 1X^h × X^H
2. 2X^h × Y
3. 3X^H × X^H
4. 4X^H × Y

Two AaBb parents are crossed. Gene A gives yellow seeds (dominant) or green seeds; gene B gives black fur (dominant) or white fur. Click the one cell for an offspring that is homozygous for yellow seeds and shows white fur.

1. 1AB × aB
2. 2AB × AB
3. 3AB × ab
4. 4AB × Ab
5. 5ab × aB
6. 6ab × AB
7. 7ab × ab
8. 8ab × Ab
9. 9Ab × aB
10. 10Ab × AB
11. 11Ab × ab
12. 12Ab × Ab
13. 13aB × aB
14. 14aB × AB
15. 15aB × ab
16. 16aB × Ab

Which cell junction seals neighbouring epithelial cells together and stops fluid leaking between them?

1. ATight junction
2. BHemidesmosome
3. CDesmosome
4. DGap junction

In Tay–Sachs disease, a ganglioside builds up in nerve cells because of a missing enzyme. In which organelle does the build-up occur?

1. ASmooth ER
2. BLysosome
3. CMitochondrion
4. DPeroxisome