10th Standard Science Chapter 9

Q1. The sequence of gradual changes which takes place in the primitive organisms over millions of years in which new species are produced is known as

Q2. If a normal cell of human body contains 46 pairs of chromosomes then the numbers of chromosomes in a sex cell of a human being is most likely to be:

(a) 60

Q3. In the human blood grouping, the four basic blood types are type A, type B, type AB, and type O. They are:

Q4. A pregnant woman has an equal chance of her baby being blood group A or blood group AB. Which one of the following shows the possible genotypes of the woman and the father of her child?

Q5. What will be the number of chromosomes present in each gamete produced by the plants if the palisade cells of a species of plant contain 28 chromosomes in all?

Q6. The following results were obtained by a scientist who crossed the F₁ generation of pure-breeding parents for round and wrinkled seeds.

From these results, it can be concluded that the actual number of round seeds he obtained was:

Q7. A cross between a tall plant (TT) and short plant (tt) resulted in progeny that were all tall plants as:

Q8. In peas, a pure tall plant (TT) is crossed with a pure short plant (tt). The ratio of pure tall plants to pure short plants in F₂ generation will be:

Q9. In human males, all the chromosomes are paired perfectly except one. These unpaired chromosomes are:

(i) Large chromosome

(ii) Small chromosome

(iii) Y chromosome

(iv) X chromosome

Q10. Which of the following determines the sex of a child?