Find CBSE Class 10 Science Solved Practice Paper for the Summative Assessment – II. These questions will not only help the students to prepare for exams in a better manner, but will also help them in understanding the depth with which a topic should be studied.
Few sample questions from the Question Paper are given below:
Q. What are Isomers? State two properties of carbon which lead to the huge number of carbon compound.
Ans. Isomers are those compounds which have same molecular formula but different structures.
For example: Pentane, C5H12, has three chain isomers as follows:
Q. How many 'X' chromosomes are present in body cells of humans in a:
Describe the role of sex chromosomes in deciding the sex of the child.
(i) A Male`s body cell contains only one X chromosome and the other one is a Y chromosome. 50 % of the male gametes (sperms) carry X-chromosome and the rest 50 % carry Y-chromosome.
(ii) A Female`s body cell contains two X- chromosomes. Female gametes (ova) contain similar type of chromosomes i.e. all carry one X- chromosome.
(iii) Sex chromosomes play a vital role in deciding the sex of the child. Males contain XY chromosomes while females contain XX chromosomes. When an egg is fertilized by a sperm carrying X- chromosome, the zygote thus developed is a female (XX condition). When an egg is fertilized by a sperm carrying Y- chromosome, the zygote thus developed is a male (XY condition).
Q. Justify the statement giving examples: ‘‘It is possible that a trait is inherited but may not be expressed.’’
Ans. Yes, it is possible that a trait is inherited but may not be expressed.
For Example: When tall garden pea plants are crossed with short pea plants, only tall pea plants are obtained in F1 generation.
Further after self pollination of tall F1 plants, both tall and dwarf plants are obtained in F2 generation in the ratio 3:1.
Reoccurrence of this character, a passive trait in F2 generation shows that this trait of short height was present in individuals of F1 but it was not expressed (due to the presence of tallness, a dominant trait.)
Q. Write the importance of ciliary muscles in the human eye. Name the defect of vision that arises due to gradual weakening of the ciliary muscles in old age. What type of lenses are required by the persons suffering from this defect to see the objects clearly?
Ans. Ciliary muscles play a vital role in altering the curvature of the eye lenses thereby adjusting the focal length of the eye lenses to enable focusing objects at varying distances.
The defect of vision that arises due to gradual weakening of the ciliary muscles in old age is called Presbyopia.
Bifocal lenses are required by the persons suffering from this defect to see the objects clearly.
Q. An object of height 5 cm is placed perpendicular to the principal axis of a concave lens of focal length 10 cm. If the distance of the object from the optical centre of the lens is 20 cm, determine the position, nature and size of the image formed using the lens formula.
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