Two crosses between the same pair of genotype or phenotypes in which the sources of the gametes are reversed in one cross, is known as

In a plant, red fruit (R) is dominant over yellow fruit (r) and tallness (T) is dominant over shortness (t). If a plant with RRTt genotype is crossed with a plant that is rrtt

A self-fertilizing trihybrid plant forms

A male human is heterozygous for autosomal genes A and B and is hemizygous for haemophilic gene h. What proportion of his sperms will be abh?

By which process there is a gain o segment of DNA which results in alteration in chromosome?

In a test cross progeny of pea plats, all were bearing violet flowers. Give the genotypes of the parent pea plants.

What do you mean by variation in biology?

Name the Indian breed of cow that was developed through artificial selection and domestication of wild cows.

Give the scientific name of the plant Mendel chose for his genetic experiments.

In a typical monohybrid cross, the F₂ population ratio is written as 3 : 1 for phenotype, but expressed as 1 : 2 : 1 for phenotype.  Explain with the help of an example.

Work out a cross to find the genotype of a tall plant.  Name the type of cross.

In dogs, black coat colour is dominant over white.  What coloured dog will you choose to breed with a given back dog, in order to find its genotype.  What is this type of cross known as?

What will be the consequence, if cytokinesis does not follow the telophase stage of cell division?  What term is given to this phenomenon?

Explain how trisomy of 21st chromosome occurs in humans.  List any four characteristic features in an individual suffering from it.

Name the genetic disorder caused by trisomy of 21 st chromosome in humans.  Write the diagnostic features of the disorder.

In cattle, hornless (H) is dominant over horned (h) and black (B) is dominant over red (b).  Consider that these two pairs of genes assort independently.
(i) What proportion of the offspring from the cross, BbHh \(\times\) bbhh, would be black and hornless?
(ii) From the cross Bbbh \(\times\) Bbhh, how many will be
(a) black and horned and 
(b) red and horned

In a test cross, AaBb \(\times\) aabb, 90 percent of the progeny are like parents.  Determine.
(i) the progeny type for the rest of the population?
(ii) Are the genes linked?
(iii) Is there any crossing over of the genes?

What exactly is dominance?  Why are some alleles dominant and some recessive?

Neha met with an accident. She was admitted to hospital where she needed blood transfusion. Due to carelessness of the hospital, she became HIV positive. What precautions should be taken during blood transfusion?

There is a 6 year old boy in a colony,who is suffering from Down's syndrom disorder Shyam is living in his neighborhood and who is kind to him and is always ready to help him but his other fellow children do not interact with him.
On the basis of above information answer following questions
(i) Is it right not to interact with the boy
(ii) What is the cause of Down's syndiom
(iii)What values are shown by Shyam?