Explain codominance with the help of one example.

Study the figures given below and answer the question


Identify in which of the crosses the strength of linkage between the genes is higher. Give reasons in support of your answer

Very briefly explain alleles

A man with blood group A married a woman with B group.They have a son with AB group and a daughter with blood group O.Work out and show the possibiliy of such inheritance

Draw the karyotype of male and female Drosophila.

A plant with red flowers was crossed with another plant with yellow flower.If \({ F }_{ 1 }\) showed all flowers orange in colour, explain the inheritance.

In a certain mammal, erect ears are dominant over drooping ears.  In a cross between the two types, out of the four offspring produced in F₂ generation, three had erect ears and one had drooping ears.  What were the genotypes of the parents? (You may represent the dominant gene as E.)

Differentiate between Homozygous and Heterozygous Conditions

Tallness of pea plant is a dominant trait, while dwarfness is the alternate recessive trait.  When a pureline tall is crossed with a pureline dwarf, what fraction of tall plants in F₂ shall be heterozygous? Give reasons.

With the help of a Punnett square, find the percentage of homozygous tall plants in a F₂ population involving a true-breeding tall and a true-breeding dwarf pea plant.

A person with trisomy of 21st chromosome shows
(i) furrowed tongue
(ii) Characteristic palm crease
(iii) rudimentary ovaries
(iv) gynaecomastia
Select the correct option, from the choices given below

The probability of all possible genotypes of offspring in a genetic cross can be obtained with the help of

A couple has two daughters. What is the probability that the third child will also be a female ?

In a dihybrid cross, if you get 9:3:3:1 ratio it denotes that:

A woman with normal vision has a colorblind father. She marries a colourblind man. What proportion of their children will be colourblind?

A heterozygous violet-flowered pea plant is crossed to another homozygous violet-flowered pea plant. What percent of the progeny plants will have the recessive trait, i.e., white flowers?

Which is correct for Turners's syndrome?

In a dihydrid cross where two parents differ in two pairs of contrasting traits like seed colour yellow (YY) and seed colour green (yy) with seed shape round (RR) and seed shape wrinkled (rr), the number of green coloured seeds (yy) among sixteen products of F₂ generation will be

Among the seven pairs of contrasting traits in pea plant as studied by Mendel, the number of traits related to flower, pod and seed respectively were

The idea of mutations was brought forth by

Test cross in plants or in Drosophila involves crossing

A person with unknown blood group under ABO system, has suffered much blood loss in an accident and needs immediate blood transfusion. His friend who was valid certificate of his own blood type, offers for blood donation without delay. What would have been the type of blood group of the donor friend?

Which one of the following symbols and its representation, used in human pedigree analysis is correct.

In a certain taxon of insects some have 17 chromosomes and the others have 18 chromosomes. The 17 and 18 chromosome-bearing organisms are :

Occasionally, a single gene may express more than one effect. The phenomenon is called :

Which of the following is correct?

Which one of the following conditions in humans is correctly matched with its chromosomal abnormality/linkage?

Which of the following conditions is related to haemophilia

Indicate, the inheritance of which of the following is controlled by multiple alleles

A human male produces sperms with the genotypes AB, ab, aB and ab pertaining to the diallelic characters in equal proportions. What is the corresponding genotype of this person?

A common test to find the genotype of a hybrid is by

Given below is the representation of a kind of chromosomal mutation

What is the kind of mutation represented?

One of the parents of a cross has a mutation in its mitochondria. In that cross, that parent is taken as a male. During segregation of F₂ progenies that mutation is found in

When a cluster of genes show linkage behaviour they

Colour blindness is a recessive sex-linked trait in which the eye fails to distinguish

A self-fertilizing trihybrid plant forms

The chromosomal disorders on the other hand are caused due to absence or excess or abnormal arrangement of one or more chromosomes. Failure of segregation of chromatids during cell division cycle results in the gain or loss of a chromosome(s), called aneuploidy (hyper or hypo). For example. Down's syndrome results in the gain of extra copy of chromosome 21. Similarly, Turner's syndrome results due to loss of an X chromosome in human females. Failure of cytokinesis after telophase stage of cell division results in an increase in a whole set of chromosomes in an organism and, this phenomenon is known as polyploidy. This condition is often seen in plants. The total number of chromosomes of a normal human being is 46 (23 pairs). Out of these 22 pairs are autosomes or body chromosome and one pair of chromosomes are sex chromosome allosome. Sometimes, though rarely, either an additional copy of a chromosome may be included in an individual or an individual may lack one of any one pair of chromosomes. These situations are known as trisomy (2n+1) or monosomy (2n−1)of a chromosome, respectively. Such a situation leads to very serious consequence in the individual.
1.Trisomy is :
A) One chromosome less than 2n
B) One chromosome more than 2n
C) A hybrid obtained by crossing diploid and tetraploid
D) Three chromosomes more than 2n
2.When a diploid female plant is crossed with a tetraploid male plant, then ploidy of endosperm cells in the resulting seed is :
A) Triploidy
B) Diploidy
C) Pentaploidy
D) Tetraploidy
3.When a diploid female plant is crossed with a hexaploid male, the ploidy of endosperm cells in the resulting seed is
A) Tetraploidy
B) Pentaploidy
C) Diploidy
D) Triploidy
4.Polyploidy can be produced artificially by :
A) Colchicine
B) Inbreeding
C) Line breeding
D) Self-pollination
5.Choose the wrong statement.
A) Failure of segregation of chromatids during cell division results in aneuploidy
B) Additional copy of 'X' chromosome in males results in Klinefelter's syndrome
C) Closely located genes in a chromosome always assort independently resulting in recombinants
D) According to Mendel, recessive character never blends in heterozygous condition

Mendel's mainly described those traits that have distinct alternate forms such as flower colour which are either purple or white. But if you look around, you will find that there are many traits which are not so distinct in their occurrence and are spread across a gradient. For example, in humans we don't just have tall or short people as two distinct alternatives but a whole range of possible heights. Such traits are generally controlled by three or more genes and are thus called as polygenic traits. F. Galton in 1883 suggested that many instances of continuous variation are heritable. He was impressed by the fact that taller humans beings generally produce taller children. He suggested that characters such as height and mental capabilities in humans are heritable although these show a continuous range of variation in a population. Gallon's postulate gained experimental support when it was found that at least in, some instances the same character can be determined by more than one gene, each with the same but cumulative or additive phenotypic effect. Quantitative characters like plant height, yield of crops (size, shape and number of seeds and fruits per plant), intelligence in human beings and milk yield in animals have been found to be determined by many genes and their effects have been found to be cumulative. Each gene has a certain amount of effect, and the more the number of dominant genes, the greater expression of the character. Though polygenic traits can be easily influenced by environment, these are generally controlled by three or more genes with phenotype reflecting the contribution of each allele.
1.Polygenic traits are controlled by how many gene(s)?
A) One gene
B) Two genes
C) Three or more genes
D) Not controlled by gene
2.Which of the following scientist is concerned with polygenic inheritance?
A) G. J. Mendel, 1856
B) Carl Corren, 1902
C) F. Gallon, 1883
D) Sturtevent, 1911
3.Many genes are controlling one trait is referred as -
A) Monogenes
B) Polygenes
C) Pleiotrophy
D) Phenotypic
4.Quantitative inheritance is due to
A) Cumulative effect
B) Additive effect
C) Both of the above
D) None of the above

Males are more susceptible to X-linked recessive traits than females. These traits can be  traced down using pedigree analysis of family. Thus, genetic counselling play a major role in the marriages these days.
(i) What are sex-linked recessive traits?
(ii) Why does X-linked recessive traits occur commonly in mnales than females?
(iii) Which symbols are used to represent affected male and consanguineous marriage in pedigree analysis?
(iv) Give an example of sex-linked dominant trait
(v) Mention one example each of autosomal dominant and autosomal recessive trait

While teaching in class, teacher told students that Mendel used the contrasting traits of pea plant to propose three basic laws of inheritance  She also said that these laws are not always universally applicable.
(i) When did Mendel performed hybridisation experiments and with how many traits of pea plants?
(ii) Which law(s) of Mendel is/are based on monohybrid cross?
(iii) Mention the phenotypic and genotypic ratios were obtained by Mendel in Monohybrid cross.
(iv) Give example of any two exceptions to Mendel's law of dominance.
(v) Which Mendel law of inheritance is universally accepted without exception?

Read the following and answer any four questions from (i) to (v) given below:
Haemophilia is a sex linked disease which is also known as bleeder's disease as the patient will continue to bleed even from a minor cut since he or she does not possess the natural phenomenon of blood clotting due to absence of anti-haemophilic globulin or factor VIII and plasma thromboplastin factor IX essential for it. As a result of continuous bleeding the patient may die of blood loss. Colour blindness is another type of sex linked trait in which the eye fails to distinguish red and green colours. Vision is however, not affected and the colour blind can, lead a normal life, reading, writing and driving (distinguishing traffic lights by their position).(i) If a haemophilic man marries a woman whose father was haemophilic and mother was normal then which of the following holds true for their progenies?

(ii) A man whose father was colourblind and mother was normal marries a woman whose father was haemophilic and mother was normal. Which of the following is true for their progenies? [Note: Percentage is from the total number of progenies.

(iii) Which of the following statements is incorrect regarding haemophilia?

(iv) Anup is having colourblindness and is married to Soni who is normal. What is the chance that their son will have the disease?

(v) Refer to the given cross

Select the correct option regarding 1, 2, 3 and 4.