5 topics · about 3 hours · 6% of the paper · asked in 4 of the last papers
22 questions from the CBSE papers we hold.
Two pea plants, one with round green seeds (RRyy) and another with wrinkled yellow (rrYY) seeds were crossed with each other which produced F_1 progeny that have only round yellow (RrYy) seeds. When F_1 plants are self-pollinated, the F_2 progeny will have which new combination of characters, as compared to the parents: (i) Round, yellow (ii) Round, green (iii) Wrinkled, yellow (iv) Wrinkled, green. Correct options are:
Study the given table and answer the following questions: [Parents: A pea plant with red flowers was crossed with a pea plant with white flowers. | F_1: 30 seeds were sown and all bore plants with red flowers. | F_2: 44 seeds were sown, 33 plants bore red flowers and 11 plants bore white flowers.] (a) Depict the information given in the table in the form of a cross. (b) Deduce the F_2 phenotypic ratio / F_2 ratio showing external look as well as genotypic/genetic makeup, ratio.
If pea plants with round and green seeds (RRyy) are crossed with pea plants having wrinkled and yellow seeds (rrYY), the seeds developed by the plants of F_1 generation will be :
Assertion (A): A human child bears all the basic features of human beings. Reason (R): It looks exactly like its parents, showing very little variations. Select the correct answer:
Mendel's experiments on inheritance in garden pea.
Write one difference between dominant and recessive trait.
Mendel's experiments on inheritance in garden pea.
In a cross with two pairs of contrasting characters RRYY x rryy (Round Yellow) (Wrinkled Green), Mendel observed 4 types of combinations in F_2 generation. By which method did he obtain F_2 generation? Write the ratio of the parental combinations obtained and what conclusions were drawn from this experiment.
Mendel worked out the rules of heredity on garden pea using visible contrasting characters, making crosses with one or two pairs of contrasting characters.
When Mendel crossed pea plants with pure tall and pure short characteristics to produce F_1 progeny, which two observations were made by him in F_1 plants?
Mendel's experiments on inheritance in garden pea.
Justify the statement: "It is possible that a trait is inherited but may not be expressed."
Chromosomes: (i) carry hereditary information from parents to the next generation. (ii) are thread like structures located inside the nucleus of an animal cell. (iii) always exist in pairs in human reproductive cells. (iv) are involved in the process of cell division. The correct statements are:
Consider the following statements: (i) The sex of a child is determined by what it inherits from the mother. (ii) The sex of a child is determined by what it inherits from the father. (iii) The probability of having a male child is more than that of a female child. (iv) The sex of a child is determined at the time of fertilisation when male and female gametes fuse to form a zygote. The correct statements are:
Mendel's pea-plant cross experiment tracing inheritance of traits.
Differentiate between dominant and recessive traits.
dihybrid cross round-yellow x wrinkled-green pea plants with new combinations appearing in F_2.
State the ratio of the combinations observed in the seeds of F_2 generation (in the above case). What do you interpret from this result?
The statement that correctly describes the characteristic(s) of a gene is:
To trace inheritance of traits Mendel crossed pea plants with contrasting characters; crossing round-yellow seed plants with wrinkled-green seed plants gave no wrinkled-green seeds in F_1, and self-pollinating F_1 gave F_2 with different combinations of seed shape and colour.
Write any two pairs of contrasting characteristics of pea plant used by Mendel other than those mentioned above.
monohybrid cross - internal choice for sub-part (c).
Given below is a cross between a pure violet flowered pea plant (V) and a pure white flowered pea plant (v). Diagrammatically explain what type of progeny is obtained in F_1 generation and F_2 generation: Pure violet flowered plant (VV) x Pure white flowered plant (vv).
Assertion (A): Genes inherited from the parents decide the sex of a child. Reason (R): X chromosome in a male child is inherited from his father. Options:
(i) In a cross between violet flowered plants and white flowered plants, state the characteristics of the plants obtained in the F_1 progeny. (ii) If the plants of F_1 progeny are self-pollinated, then what would be observed in the plants of F_2 progeny? (iii) If 100 plants are produced in F_2 progeny, then how many plants will show the recessive trait?
What is variation? List two main reasons that may lead to variation in a population.
Sex-determination in humans: humans have 46 (23 pairs) chromosomes; 44 (22 pairs) control body characters and 2 (one pair) are sex chromosomes of two types - X chromosome and Y chromosome; at fertilisation the type of male gamete that fuses with the female gamete decides the sex of the newborn. Why is a pair of sex chromosomes in human beings called a mismatched pair in terms of type and size?
Sex-determination in humans (46 chromosomes: 44 autosomes + 2 sex chromosomes X and Y; sex of newborn decided by which male gamete fuses with the female gamete). Out of male or female, which of them has a perfect pair of sex chromosomes? In case of a perfect pair, will the gametes produced be of the same kind or of a different kind?
Sex-determination in humans (46 chromosomes: 44 autosomes + 2 sex chromosomes X and Y; sex of newborn decided by which male gamete fuses with the female gamete). Write the names of two organisms whose sex determination is not done on a genetic basis. Explain the process of their sex determination.
Sex-determination in humans (46 chromosomes: 44 autosomes + 2 sex chromosomes X and Y; sex of newborn decided by which male gamete fuses with the female gamete). With the help of a flow chart only, show how sex determination in human beings takes place genetically.