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Which of the following statements about reproduction in humans is correct? (a) Fertilisation takes place externally. (b) Fertilisation takes place in the testes. (c) During fertilisation, egg moves towards the sperm. (d) Fertilisation takes place in the human female.

d) Fertilisation takes place in the human female (oviduct). The female reproductive system is framed to perform different functions. It creates... View Article

Why does moon have very cold and very hot temperature variations eg., from -190°C to 110°C even though it is at the same distance from the sun as the earth is?

The moon has no atmosphere, unlike Earth. The energy from the Sun heats up the land as well as the air; hence the temperature does not drop too... View Article

One of the following processes is not a step involved in the water-cycle operating in nature (a) evaporation (b) transpiration (c) precipitation (d) photosynthesis

d) Photosynthesis There are many processes involved in the movement of water. Listed below are different stages of the water cycle. The sun... View Article

Bacteria do not have chloroplast but some bacteria are photoautotrophic in nature and perform photosynthesis. Which part of the bacterial cell performs this?

Bacterial cell do not have chloroplast but yet some photoautotrophic bacteria perform photosynthesis due to the presence of chlorophyll in... View Article

When air is contaminated by substances which have a effect on both the and , it is referred to as . (air pollution, harmful, living, unwanted, non-living, pollutants).

When air is contaminated by unwanted substances which have a harmful effect on both the living and non-living, it is referred to as air... View Article

Is the following statement correct? If it is wrong, correct the statement Statement : “Unicellular organisms do not respire, only multicellular organisms respire”

The given statement is wrong, as all the species or organisms respire. Both unicellular and multicellular organisms respire. Cellular... View Article

In a synapse, a chemical signal is transmitted from (a) dendritic end of one neuron to axonal end of another neuron (b) axon to the cell body of the same neuron (c) cell body to axonal end of the same neuron (d) axonal end of one neuron to dendritic end of another neuron

(d) axonal end of one neuron to dendritic end of another neuron In a synapse, the electrical signal is 'translated' into the neurotransmitter... View Article

Paheli dug two pits, A and B, in her garden. In-pit A, she put a polythene bag packed with some agricultural waste. In-pit B, she dumped the same kind of a waste but without packing it in a polythene bag. She then covered both the pits with soil. What did she observe after a month? (a) Waste in pit A degraded faster than that in pit B. (b) Waste in pit B degraded faster than that in pit A. c) Waste in both pits degraded almost equally. (d) Waste in both pits did not degrade at all.

b) Waste in pit B degraded faster than that in pit A. When compared to pit A, pit B degraded faster because it was kept open and that's why it... View Article

Classify the following based on number of chambers in their heart. Rohu, Scoliodon, Frog, Salamander, Flying lizard, King Cobra, Crocodile, Ostrich, Pigeon, Bat, Whale.

2-Chambered Heart-Rohu, Scoliodon 3-Chambered Heart-Frog, Salamander, Flying lizard, king cobra 4-Chambered Heart-Crocodile, Ostrich, Pigeon,... View Article

Which muscles act involuntarily? (i) Striated muscles (ii) Smooth muscles (iii) Cardiac muscles (iv) Skeletal muscles (a) (i) and (ii) (b) (ii) and (iii) (c) (iii) and (iv) (d) (i) and (iv)

b) (ii) and (iii) Smooth muscles are found in the walls of hollow visceral organs. They do not work according to our will. They are involved in... View Article

The Red Data Book keeps a record of all the (i) endemic species. (ii) extinct species. (iii) endangered plants (iv) endangered animals. (a) i & ii; (b) ii & iii; (c) iii & iv; (d) i & iv

(c) iii & iv Endangered animals and plants 'Red Data Book' contains lists of all the species of plants and animals whose continued... View Article

The metal which produces hydrogen gas on reaction with dilute hydrochloric acid as well as sodium hydroxide solution is (a) Copper (b) Iron (c) Aluminium (d) Sodium

(c) Aluminium reacts with hydrochloric acid as well as sodium hydroxide solution to produce hydrogen gas. Aluminium oxide is amphoteric. It acts... View Article

Give a suitable word for each of the following statements. (a) The site which response to a hormone. (b) Name of a gland which transports secretions through ducts. (c) Chemicals which control changes at the adolescence stage. (d) It marks the beginning of the reproductive period.

(a) The site response to a hormone - Receptor Receptors are defined as specialized structures found in the cell membrane. They are mainly... View Article

The inner lining of the stomach is protected by one of the following from hydrochloric acid. Choose the correct one (a) Pepsin (b) Mucus (c) Salivary amylase (d) Bile

b) Mucus The inner lining of the stomach is protected by the mucus secreted by mucoid cells present in the cardiac and pyloric regions of the... View Article

The muscular tissue which functions throughout the life continuously without fatigue is (a) skeletal muscle (b) cardiac muscle (c) smooth muscle (d) voluntary muscle

b) Cardiac muscle Cardiac muscle is a type of involuntary striated muscle found only in the walls of the heart. This is a specialized muscle... View Article

The type of pollution which is likely to affect Taj Mahal in Agra to a greater extent is (a) air pollution (b) water pollution (c) soil pollution (d) noise pollution

a) Air pollution The type of pollution which is likely to affect Taj Mahal in Agra to a greater extent is air pollution. It is... View Article

During deficiency of oxygen in tissues of human beings, pyruvic acid is converted into lactic acid in the (a) cytoplasm (b) chloroplast (c) mitochondria (d) Golgi body

(a) cytoplasm Pyruvic acid is converted into lactic acid in the cytoplasm of muscle cells during deficiency of oxygen in human beings.Pyruvic... View Article

Which of the following can make you ill if you come in contact with an infected person? (a) High blood pressure (b) Genetic abnormalities (c) Sneezing (d) Blood cancer

c) Sneezing Through sneezing, the water droplets carrying the microbes enter into the healthy person. All the others are non communicable... View Article

Which of the following cell organelle is found in all plant cells, animal cells and also in bacterial cells? (a) chloroplast (b) cell wall (c) cell membrane (d) nucleus

(c) cell membrane The plant and animal cells are eukaryotic and contain well-developed cellular organelles. The cell membrane, cytoplasm,... View Article

Choose the incorrect statement from the following. Forest fires are usually due to: (a) carelessness of humans (b) heat of sun (c) cutting of trees (d) lightning strike

(c) cutting of trees One of the main reasons for the forest fire is the hands of human beings. Most fires that are started by natural causes are... View Article

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