Sex of a baby is determined by the chromosomes which it receives from the male. Males have two types of gametes one with X-chromosome and other with Y-chromosome. If a sperm (gamete) with X-chromosome fertilizes the egg, the zygote would develop into female and if a sperm with Y-chromosome fertilizes the egg, the zygote would develop into male.

The stars forming a group that has recognizable shape are called a constellation. Ursa major and Orion.

Consequences of deforestation:
(i) Deforestation increases the temperature and pollution level on the earth. It increases the level of carbon dioxide in the atmosphere.
(ii) It also disturbs the balance in nature and increases chances of natural calamities such as floods and droughts.

The sound travels through the different mediums i.e., solid, liquid or gases.

Run-off from a garden is not considered a point source of pollution because this water does not have a specific location for its discharge pollutants.

The banana appears yellow because it reflects red and green light but absorbs blue light.

Acids, bases and salts.

On a wet marble, floor, frictional force between the foot and floor decreases making it slippery, thus we feel difficult to move on a wet marble floor.

We get conclusion from this observation that the object has an electric charge on it.

We do not feel atmospheric pressure on our body. It is due to the pressure inside our body is nearly equal to atmospheric pressure.

A fertilised egg is also called zygote.

Cell membrane or plasma membrane gives shape to a cell.

Candle burns with a flame whereas coal does not.

Phosphorus.

Nylon

Coke

In the soil, nitrogen is enriched by blue-green algae (cyanobacteria).

Yes, cultivator has an advantage as its use saves time as well as labour by digging into a considerable area at the same time.

Electroplating is the process of depositing a layer of any desired metal on another metal by means of electricity.
Advantages of electroplating:
(i) It is used to coat a desired metal on another metal.
(ii) It protects the metals from corrosion.
(iii)It also prevents the metallic surface from rusting.
(iv) Some cheap and dull metals are coated with costly and shinning metals for ornamental use.
(v) It can make more reactive metals like iron less reactive.
(vi) Coating of chromium on metals gives luster to object

Factors affecting friction:
(i) It depends on the nature of surfaces in contact.
(ii) It is more between rough surfaces and less between smooth surfaces.
(iii) It depends on how hard the two surfaces press together.
(iv) It is independent of the area of contact.

Plants utilise CO₂ from the atmosphere for photosynthesis, thereby decreasing the amount of CO₂ in the air. Deforestation leads to an increase in the amount of CO₂ in the air because the number of trees which consume CO₂ is reduced. Human activities thus contribute to the accumulation of CO₂ in the atmosphere. CO₂ traps heat and it doesn't allow it to escape into space. As a result, the average temperature of the atmosphere is gradually increasing. This is called global warming. Thus, increased CO₂ contributes to global warming.

Gene is a unit of inheritance in living organism. It controls the transfer of hereditary characteristics from parents to offsprings.
This means that your parents pass some of their characteristics to you. If your father has brown eyes, you may have brown eyes. However, the different combination of genes from parents results in different characteristics.

Cloning is the production of an exact copy of a cell any other living part, or a complete organism. Ian Wilmut and his colleagues at the Roslin Institute, Edinburgh, Scotland successfully cloned a sheep named Dolly.
Following steps were involved in cloning:
(i) A cell was collected from the mammary gland of a female sheep.
(ii)An egg was obtained from a Scottish blackface and its nucleus was removed.
(iii)The nucleus from the mammary gland cellof Dorset sheep was introduced in the egg.
(iv)This egg was then implanted in the uterus.

(i) The continuity of the forest is distributed animals get confined to smaller area. This leads to fragmentation of species and disturbance to the ecological balance. The noise of the vehicles will disrupt the silence of the forest, forcing the animals to move out into human habitations.
(ii) Forests are useful to mankind due to following reasons:
(a) Provide us fresh air and a wide variety of flora and fauna.
(b) Sources of various products such as paper, fibre, medicines etc.
(c)Keep the environment healthy and beautiful.
(iii) Amit has love for nature and environment. He is intelligent, calm and focussed.

Micro-organisms are" also very harmful to us. They cause a number of diseases in humans as well as in other animals. Common cold, Tuberculosis, Measles, chicken pox, polio, cholera, typhoid, hepatitis-B. malaria are some common human diseases caused by micro-organisms. Anthrax is a serious disease in animals caused by microbes. They also make food items unfit for use by food poisoning. They also spoil clothes and leather products. They also cause diseases in plants like blights in potatoes, sugarcane, oranges, etc. They also reduce the crop production.

Kaleidoscope is a cylinder with mirrors containing loose, coloured objects such as beads or pebbles and bits of glass. As the viewer looks into one end, light entering the other creates a colourful pattern due to reflection. Its applications are given below:
(i) It works on the principle of multiple reflections, where several mirrors are placed at an angle (usually 60°) to one another. Typically, these are three rectangular mirrors set at 60° to each other so that they form an equilateral triangle.
(ii) The 60° angle creates seven duplicate images of the objects, 5 at 60° and 2 at 90°. As the tube is rotated, the tumbling of the coloured objects presents varying colours and patterns.
(iii) It is used in decoration purposes, toys, etc.

Height of a child depends upon the genes inherited from parents. However, there are some other factors also that can affect height. These factors include balanced diet, hormones, exercise, diseases. Balanced diet is essential for the adolescents as it helps the bones, muscles and other parts of the body to get adequate nourishment for growth.
Similarly, lack of hormones as growth hormones may lead to dwarfism. Regular exercise is also essential for proper development lack of disease is a priority for proper growth that is related to other factors listed above. Thus, height depends on combination of various factors.

The tail of the comet is always directed away from the Sun. The tail will be longest in the position B because the tail is visible only when the comet passes through the inner solar system and B is nearest.

(a) Here, F = 50N, A = 5 cm² = 5 x10^-4 m²
\(\therefore p=\frac{F}{A}=\frac{50}{5\times10^{-4}}=10^{5}\) Pa
(b) Here, area changes to 50 cm²= 50 x 10^-4 m²
\(\therefore p=\frac{F}{A}=\frac{50}{5\times10^{-4}}=10^{4}\)Pa
(c) Here the values displayed by the teacher is the experience and his ideality.

As we know that the speed of sound in air is about 340 m/s and the speed of light in air is 300,000,000 m/s. It means that sound travels at a slow speed while light travels much faster than sound.

So, though sound may take a few seconds to travel a distance of a few hundred metres, light will take practically negligible time to reach a distance of even a few kilometres. e.g. in the rainy season, the flash of lightning is observed first and the sound of thunder is heard a little later (though both are produced at the same time in clouds) (see figure). It is because of the very high speed of light that we see the flash of lightning first and it is due to comparatively low speed of sound that the thunder is heard a little later.

Since ebonite rod acquires charge when rubbed. So, the Charge transfer will be either too less or there will be no transfer of charges, so the strips of aluminium will not be wider and we are not able to predict the object whether it is charged or not.

Take about 50 mL of water in a beaker and dissolve 5 g of copper sulphate in it to obtain copper sulphate solution (which is blue in colour). Put a clean iron nail in this solution and keep the beaker undisturbed for sometime.
We will find that the blue colour of copper sulphate solution starts fading gradually and the iron nail gets covered with a red-brown layer of copper metal. It is because iron is more reactive than copper, so it displaces copper metal from its solution of copper sulphate. It is the copper metal set free from its compound which forms a red-brown layer on the surface of iron nail. This shows that iron is more reactive than copper.
Copper sulphate + Iron\(\rightarrow \) Iron sulphate + Copper
(Blue solution)      (Grey) (Greenish solution) (Red-brown)

(a) Coal.
(b) It is solid and black coloured.
(c) Y is carbonisation and Z is destructive distillation.
(d) A is coke, B is coal gas while C is coal tar.

(a) Sometimes, the animals (like cow) eat up the polythene bags and wrappers of food along with the left-over food thrown on garbage dumps.
(b) To deelop habits which are environment friendly one should follow 4 R principle which stands for reduce, reuse, recycle and recover.
(c) Karan followed his mother's advice, it shows that he is an intelligent, obedient caring and responsible boy

(a) Paddy is cultivated in rainy season as it is a kharif crop.
(b) For sowing paddy, seeds are first grown in a nursery and later seedling are transplanted in the field. This allows us to select only healthy and better seedlings for cultivation.
(c) Measures taken to prevent spoilage or damage of harvested crops from insect attack are:
(i) Exposing them in sunlight for drying as freshly harvested crops have moisture.
(ii) Dried neem leaves are added to stored grains, so as to prevent damage from pests.
(iii) Specific chemical treatments are also available for preventing crops.

Human eye: The eye has a roughly spherical shape. The outer coat of eye is white. Its transparent front part is called cornea. Behind cornea a dark muscular structure is situated called iris. There is a small opening called the pupil. The size of the pupil is controlled by the iris. The iris controls the amount of light entering into the eye. The lens focuses light on the back of the eye, on a layer called retina. The retina contains several nerve cells. They transmit impulses to the brain through the optic nerve and hence, image is formed.

Immunization is the development of resistance against a pathogen. It is carried out through vaccination. Regular vaccination will eradicate diseases from a country. For example PPIP (Pulse Polio Immunization Programme). It is the largest public health programme launched in December 1995 in an attempt to eradicate polio from our country.

Plastics take several years to decompose, so they are not environment-friendly. Plastic causes environmental pollution. Besides, the burning process of synthetic material is quite slow and it does not burn completely. In this way, it releases lots of poisonous fumes in the atmosphere causing air pollution.

Differences between fertilizer and manure:

False, we can survive for some time without food but we cannot survive even for a few minutes without air.

If the liquid between the two ends of a tester allows the electric current to pass, then the circuit of the tester becomes complete. The current flow in the circuit and the bulb glows. When the liquid does not allow the electric current to pass, the circuit of the tester is not complete and the bulb does not glow

When sun is shifting towards the south, then it is called dakshnayan and when the sun shifts towards the south, it is called uttarayan. So, the Sun shifts towards the south from 21 st June and it starts shifting towards north from 22nd December.

Since, in seismic zones, all the houses and buildings should be designed and constructed in such a way, so that they can withstand major earthquake tremors.

Hearing impairment means a person has damaged hearing ability and cannot hear properly. There are some people who born with poor hearing ability. A person with very poor hearing ability is said to be deaf. So, deafness is total hearing impairment.

Sperm is a male reproductive cell. It is also called a male gamete. It is a single cell with all cell components. It is tiny with a head, a middle piece and a tail. The long tail helps to move through the female tract.

(a) A is chloroplast and B is cell wall.
(b) C is chlorophyll and D is cellulose.
(c) Chloroplast (A) is present only in plant cell. It contains a green pigment, called chlorophyll (C) which helps in photosynthesis and also provides green colour to its leaves.

Some tribals depend on the jungle because they get almost of their resource to live from the jungle like shelter, wood, food, etc.

Adolescence is the period of life, in which organisms become reproductively active. In other words, it is the period of attaining reproductive maturity in boys and girls, which starts from 11-13 years and lasts upto 18-19 years in humans.

(a) A is sodium hydrogen carbonate (baking soda).
(b) The heat of fire decomposes sodium bicarbonate to produce carbon dioxide gas which covers the fire like a blanket. It cuts off supply of fresh air to the burning substance. Thus, fire gets extinguished.
(c) Potassium hydrogen carbonate behaves like A.

Gold is a metal which is washed or polished in acidic solution. During the process of polishing, some gold dissolves in acid to form oxide. This causes the loss of gold from the jewellery.

Fossil fuels are exhaustible natural resources because they are made by the decomposition of the dead remains of living organisms. These are present in limited quantity beneath the earth. Thus, it will come to an end by human usage.