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| bpsir.blogspot.com cbse online solution |
1.How is the sex of a new born determined genetically in humans?
2.State the cause of dispersion, when white light enters a glass prism. Explain with a diagram.
3.(a) Draw the structures for the following compounds. (i) 2- Bromopentane
(ii) 2 – methyl-propane
(iii) Butanal
(iv) 1 – Hexyne
(b) Draw the electron dot structure for ethanoic acid. (c) Draw and explain the structure of the micelle. Which end of the micelle dissolves in dirt ?
4.(a) Write a test to distinguish between Ethanol and Ethanoic acid.
(b) Draw electron dot structure of ethane.
(c) Why do soaps form scum with hard water ?
5.A person can see distant sign boards clearly but cannot read clearly a book which is at 25 cm from his eye. Identify the defect. Draw a labelled ray diagram to illustrate how this defect can be corrected.
6.(a) Draw the longitudinal section of a flower and label the following parts.
(i) stigma (ii) style (iii) anther (iv) ovary
(b) Why are papaya flowers called unisexual ?
(c) After fertilization in a flower, mention the structures that develop into the embryo and seed.
7.(a) Define power of a lens.
(b) An object is kept at a distance of 18cm, 20cm, 22cm, and 30cm, from a lens of power +5D.
(i) In which case or cases would you get a magnified image?
(ii) Which of the magnified image can be got on a screen?
(c) List two widely used applications of a convex lens.
8.(a) Define principal focus, focal length and principal axis of a lens.
(b) Draw ray diagrams to show the principal focus of a (i) convex lens (ii) concave lens
9.(a) Give reasons :-
(i) Wind acts as a pollinating agent.
(ii) Variation is essential and beneficial to a species.
(iii) Use of condoms prevents pregnancy.
(b) Draw a neat diagram of human male reproductive system and label its four important
parts.
(i) Wind acts as a pollinating agent.
(ii) Variation is essential and beneficial to a species.
(iii) Use of condoms prevents pregnancy.
(b) Draw a neat diagram of human male reproductive system and label its four important
parts.
10.(a) In the male reproductive system, where is the organ that produces male germ cells situated ? Why?
(b) Mention the role of prostate gland and seminal vesicles in the human male reproductive system. (c) How are the male and female germ cells produced in the human body different from each other ?
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