Although albinos have poor vision yet they lead normal life. Female with more than two X chromosomes is called superfemale. Here, an extra copy of chromosome 21 occurs. A few instances of such inheritance are skin colour in human beings, human intelligence, height in human beings etc. A diseased man marries a normal woman.
A marriage between normal visioned man and colour blind woman will produce offspring a colour blind sons and 50% carrier daughter b 50% colourblind sons and 50% carrier daughter c normal males and carrier daughters d colour blind sons and carrier daughters. The more the X chromosomes, the greater is the mental defect. Three of the sons suffer from the given disease but none of the daughters affected. Gonads and genita are undeveloped. The sex of a human is determined by a. It is perhaps the smallest gene occupying only 14 base pairs.
Quantitative inheritance is a type of inheritance controlled by one or more genes in which the dominant alleles have cumulative effect with each codominant allele expressing a part or unit of the trait, the full trait being shown only when all the dominant alleles are present. Both sickle-cell anaemia and thalassemia are more common in malaria areas, because these mutations convey some protection against the parasite. It is not at all hereditary. The individual has 45 chromosomes 44 + X instead of 46. Erythroblastosis foetalis is caused when fertilization takes place between gametes of a Rh female and Rh + male b Rh + female and Rh — male c Rh + female and Rh + male d Rh~ female and Rh — male. Presence of one extra chromosome in female.
None of the above 13. It is designed to help you learn the material. Practice Quiz for Mendel's Genetics No. In a simple Mendelian monohybrid cross, tall plants were crossed with short plants and the F1 were crossed among themselves. Affected males have an extra X sex chromosome. Pattern baldness, moustaches and beard in human males are examples of a sex-linked traits b sex limited traits c sex influenced traits d sex determining traits Answer and Explanation: 36.
Mutant alleles of this gene cause the eyes to be brown instead of red. Both Rh + and Rh+ individuals are phenotypically normal. As a result, erythrocytes having haemoglobin-S become sickle-shaped. Sickle cell anemia caused by the presence of mutantallele in ----chromosome a. Affected males are almost always effectively sterile, although advanced reproductive assistance is sometimes possible and some degree of language learning impairment and mental retardation may be present.
How could mutants such as these play a role in the evolution of reproductive isolation between populations? A response will appear in the window below the question to let you know if you are correct. Both a and c 24. A colour blind girl is rare because she will be born only when a her mother and maternal grandfather were colour blind b her father and maternal grandfather were colour blind c her mother is colour blind and father has normal vision d parents have normal vision but grandparents were colour blind. Intersex is an individual who shows anatomical characteristics of both sexes. The gene of this disease is a sex linked dominant b sex linked recessive c sex limited character d autosomal dominant.
Answer: a may be colourblind or may be of normal vision 40. The differential region of Y-chromosome carries only Y-linked or holandric genes, e. The normal gene and its recessive allele are carried by X-chromosomes. Possible genotypes of the father are: a. What is the probability that their second child will also be an albino? Sickle-cell anaemia and phenylketonuria are due to recessive genes autosomal in homologous condition. Albinism is known to be due to an autosomal recessive mutation.
It appears in about in 7000 males. The normal gene and its recessive allele are carried by X- chromosomes. Phenylketonuria is an inherited error of metabolism caused by a deficiency in the enzyme phenylalanine hydroxylase. Who was the first map to chromosomes? The dark moths carry a dominant allele, and the light moths are homozygous for a recessive allele. Answer: b sex-linked recessive 44. The abnormal cells are short-lived, which causes anaemia and become lodged in capillaries, which reduce the blood supply to organs. Colourblindness is produced by a recessive gene lying on X-chromosome.
Sex linked traits are those traits the determining genes of which are found on the sex chromosomes. Such persons are sterile males with undeveloped testes, mental retardation, sparse body hair, and long limbs and with some female characteristics such as enlarged breasts. Harry Klinefelter, an endocrinologist at Massachusetts General Hospital, Boston, Massachusetts, who first described it in 1942 the condition, exists in roughly 1 out of every 500 to 1,000 males. How will the progeny be? On the other hand, the mosquito borne disease is malaria. Homologous regions of the two help in pairing. Sickle cell anaemia is not a sex linked i. This is a serious problem.
A woman with normal vision, but whose father was colour blind, marries a colour blind man. If a male has one recessive allele, he will show that trait, but it will take two recessive alleles for the female to show that same trait e. Haemophilia A is the most common X-linked genetic disease that prevents normal blood clotting when blood vessels are ruptured. Many other missense mutations have been described which do affect the encoded protein and result in genetic diseases. Down syndrome is a relatively common birth defect caused by the presence of an extra chromosome number 21 three instead of two number 21 chromosomes, or trisomy 21. It is characterised by rounded face, broad fore-nead, permanently open mouth protruding tongue, projecting lower lip, short neck, Hat hands and stubby small lingers, mongolian type eye lid fold.