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True or False

Debate and discussion of any biological questions not pertaining to a particular topic.

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True or False

Postby Grace » Sat Dec 04, 2004 12:59 pm

Hey guys,

I've completed nearly all the questions, except for questions 12, 13, 22, 23. Could you guys check to see if my answers are correct, and answer the unaswered ones? Thanks!

1. The gene make-up of an organism for a particular trait is its genotype. T
2. The appearance of an organism is its genotype. F
3. Each parent contributes one of the genes for a particular trait. T
4. The gene pairs in the zygote are called alleles. T
5. In human beings a child’s sex is determined primarily by the male. T
6. The offspring of the P1 are the P2 generation. T
7. Down’s syndrome was formally called Hemophilia. F
8. The phenotypes of the homozygous black Guinea Pigs and the heterozygous black Guinea Pigs are black. T
9. Purebred red-flowered plants crossed with purebred white-flowered plants produce red-flowered offspring, making the gene for red flowers dominant. F
10. In the year 1902 Sutton came to the conclusion that Mendelian Heredity could be explained if the function of the mitochondria were known. T
11. Identical twins have many similar characteristics mainly because they were exposed to the same parental environment. F
12. The Rhesus, Rh-positive can be found in the 85% of the causoid race.
13. The ABO blood incompatibility is much more severe than the Rh type.
14. Carbohydrates play an important part of the DNA template formation. T
15. The degree to which the gene is expressed depends on the environment. F
16. Expression of the gene for hereditary baldness requires the presence of the female sex hormone. T
17. A man who carries a sex-linked gene on his y chromosome will transmit it to all his male offspring. T
18. Support for Mendels belief that elements controlling heredity exist in pairs was found in the study of the process of fertilization. T
19. In all conditions where the defective gene is on the X chromosome, transmission to a female can ONLY be through the father. F
20. The hereditary factors which an individual will pass on his offspring are determined by his cytoplasm. F
21. When a color-blind man marries a homozygous normal-vision woman, the chances of their having color are zero. T
22. If a single white-flowered plant appears in the sixth generation of a purebred red-flowered plant a mutation would have occurred.
23. If a white-eyed Drosophila were crossed with a female red eye the F1 generation would have all white-eyes.
24. The best type of crossing is one in which the organism to be tested is mated with an organism that is homozygous recessive for the trait in question. T
25. A mother of blood type A and father of blood type B have a child of type 0. this was due to the fact that the father is homozygous B. F
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Postby biostudent84 » Sat Dec 04, 2004 5:39 pm

6. False. Offspring of the P generation is the F1 generation, the offspring of F1 is F2
11. Partially true. Twins raised by the same parents will be more identical than twins separated at birth
12. True
13. False. Rh HAS to be identical, ABO can be different
15. True in some cases
22. Possibly true
23. True if white-eyes are dominant. False if red-eyes are dominant
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Postby Dr.Stein » Thu Jul 07, 2005 10:31 am

23. False.
The gene for red-eyed in Drosophila is dominant and is a X-linked gene.

- The white-eyed Drosophila must be a male parent (P)
- There are two possibilities for a red-eyed female P Drosophila: homozygous or heterozygous.
---> If the female P is homozygous, both all male offsprings and female offsprings (F1) will be red-eyed.
---> If in this case the female P is heterozygous, all male F1 will be white-eyed whereas all female F1 will be red-eyed.

In X-linked gene, there is a pattern of inheritance called "Criss Cross", in which female F1 will inherit defective gene from their male P, otherwise male F1 will inherit defective gene from their female P.
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