NCERT
- The anther contains (a) sepals. (b) ovules. (c) carpel. (d) pollen grains. Correct option is d) pollen grains. The anther contains pollen grains. 1
- Which of the following is not a part of the female reproductive system in human beings ? Correct option is c) Vas deferens Vas deferens is not a part of the female reproductive system in human beings . 1
- Asexual reproduction takes place through budding in (a) amoeba. (b) yeast. (c) plasmodium. (d) leishmania. Correct option is b) yeast Asexual reproduction takes place through budding in yeast 1
- If a woman is using a copper-T, will it help in protecting her from sexually transmitted diseases? No, because copper-T will not prevent contact body fluids. Thus it will not protect her from sexually transmitted diseases. 1
- How does the embryo get nourishment inside the mother's body? After fertilization the lining of uterus thickens and is richly supplied with blood to nourish the growing embryo. The embryo gets nutrition... 1
- What are the changes seen in girls at the time of puberty? The changes seen in girls at the time of puberty are: Increase in breast size and darkening of skin of the nipples present at the tips of th... 1
- What is the role of the seminal vesicles and the prostate gland? The secretions from seminal vesicles and prostate glands lubricate the sperms and provide a fluid medium for easy transport of sperms. Their... 1
- How is the process of pollination different from fertilization? Pollination is the process of transfer of pollens from anther to stigma. It occurs with the help of certain pollinators such as air, water,... 1
- Why is DNA copying an essential part of the process of reproduction? DNA copying is an essential part of reproduction as it passes genetic information from parents to offspring. It determines the body design o... 1
- Why is vegetative propagation practised for growing some types of plants? Vegetative propagation is practiced for growing some types of plants because of following advantages: It is used to grow a plant in which vi... 1
- Can you think of reasons why more complex organisms cannot give rise to new individuals through regeneration? Higher complex organisms cannot give rise to new individuals through regeneration because complex organisms have organ-system level of organ... 1
- How will an organism be benefited if it reproduces through spores? Advantages of spore formation: Large numbers of spores are produced in one sporangium. Spores are distributed easily by air to far-off place... 1
- How does binary fission differ from multiple fission? In binary fission a single cell divides into two equal halves.Amoeba and Bacteria divide by binary fission. In multiple fission, a single ce... 1
- Why is variation beneficial to the species but not necessarily for the individual? Variations are beneficial to the species than individual because sometimes for a species, the environmental conditions change so drastically... 1
- What is the importance of DNA copying in reproduction? DNA is the genetic material present in the cells of all organisms. The genetic information from generation to generation is carried by DNA.... 1
- Why does the sky appear dark instead of blue to an astronaut? The sky appears dark instead of blue to an astronaut because there is no atmosphere in the outer space that can scatter the sunlight. As the... 1
- Why does the Sun appear reddish early in the morning? During sunrise, the light rays coming from the Sun have to travel a greater distance in the earth's atmosphere before reaching our eyes. In... 1
- Explain why the planets do not twinkle? Planets are much closer to the earth and are seen as extended sources. So, a planet may be considered as a collection of a large number of p... 1
- Why do stars twinkle? Stars twinkle due to atmospheric refraction of starlight. As the stars are very far away, they behave as almost point sources of light. A so... 1
- What happens to the image distance in the eye when we increase the distance of an object from the eye? The image is formed on the retina even on increasing the distance of an object from the eye. For this eye lens becomes thinner and its focal... 1
- Why is a normal eye not able to see clearly the objects placed closer than 25 cm? A normal eye is unable to clearly see the objects placed closer than 25 cm because the ciliary muscles of eyes are unable to contract beyond... 1
- Make a diagram to show how hypermetropia is corrected. The near point of a hypermetropic eye is 1 m. A person suffering from hypermetropia can see distinct objects clearly but faces difficulty in seeing nearby objects clearly. It happens bec... 1
- The far point of a myopic person is 80 cm in front of the eye. What is the nature and power of the lens required to https://youtu.be/21zM3lHSEHg 2
- A person needs a lens of power -5.5 dioptres for correcting his distant vision. For correcting his near vision he The power P of a lens of focal length f is given by the relationP= 1/f (i) Power of the lens used for correcting distant vision = - 5.5 D Fo... 1