Reaching the age of adolescence

Q1) what is puberty?

Ans: the process of physical changes by which an individual becomes capable of reproduction is called puberty.

Q2) which is the male sex hormone?

Ans: testosterone

Q3) which female organ produces estrogen and progesterone hormone

Ans: ovaries

Q4) which male organ produces testosterone

Ans: testes

Q5) what is the normal duration of menstrual cycle?

Ans: 28 to 30 days.

Q6) what is menopause?

Ans: at about 50 years of age, the menstrual cycle stops. This is known as menopause.

Q7) During which phase of the menstrual cycle is a mature egg released by one of the ovaries?

Ans: During the mid-cycle normally one mature egg cell is released by the ovary.

Q8) which pair of chromosomes determines the sex of a male and a female child?

Ans: sex chromosomes.

Q9) why do acne and pimples erupt on the skin during puberty?

Ans: during puberty, there is an increase in the activity of sweat and oil glands. The skin becomes oily and acne and pimples may erupt on the skin.

Q10) Differentiate between exocrine and endocrine glands?

Ans: Exocrine glands: the glands that releases its secretions with the help of a duct at a specific place is called an exocrine glands.

For example, the salivary glands secrete saliva in the mouth with the help of salivary duct.

Endocrine glands: the human body has several endocrine glands. They are pituitary glands, hypothalamus, thyroid

Gland, parathyroid gland, adrenal gland, pineal gland and reproductive glands.

The testes in the male and ovaries in the female form the reproductive endocrine glands.

Q11) Explain with an example why the pituitary glands is called the master gland?

Ans: the pituitary gland is called the master gland as its hormones control the activities of many other endocrine glands.

For example, the pancreas and adrenal glands are simulated by the pituitary gland to create insulin and adrenaline respectively.

Q12) why do tadpoles that grow in water deficient in iodine fail to develop into adult frog?

Ans: in frogs, metamorphosis is controlled by thyroxine produced by the thyroid gland, iodine is required for the proper production of thyroxine. This is why tadpoles that grow in water that id deficient in iodine fail to develop into adult frog.

Q13) list two ways by which young people may refrain from indulging in undesirable activities?

Ans: play outdoor games, develop hobbies such as painting, singing, photography, gardening or playing music. Awareness of the addictive nature of bad habits and their consequences will also help one to stay out of such activities.

Q14) write a short note on puberty in boys and girls.

Ans: in girls, during puberty, the hormones estrogen and progesterone develop female sexual features. The breasts begin to develop and the body becomes more rounded, especially the hips. The growth of the body accelerates and girls begins menstruating.

During puberty in boys, hormones from the pituitary gland and testosterone bring about the physical changes that make a boy mature into an adult male.

Q15) Explain the menstruation cycle in girls.

Ans: once a girl is an adolescent, menstruation occurs regularly once in about 28 to 30 days. This regular physiological process is called menstrual cycle. Menstruation begins at puberty. The first menstruation is termed menarche. In the beginning cycle may be irregular. After sometime it becomes regular. The menstrual cycle is controlled by certain hormones. During the mid-cycle normally one mature egg cell is released by the ovary. If the egg gets fertilized, it gets embedded in the uterus and begins to develop.

During each menstrual cycle, the wall of the uterus prepares to receive a fertilized egg. The uterine wall thickens and is richly supplied by additional blood vessels.

Q16) what is the importance of diet during adolescence?

Ans: a balanced diet of an adolescent should include the required amounts of carbohydrates, proteins, fats, vitamins and minerals to meet the needs of rapidly developing body. Food items like pulses, mushrooms, milk, eggs, fish and meat are rich in proteins.

Q17) How is the gender of a child determined ?

Ans: being a male or a female is dependent on the particular pair of chromosomes.

This pair is known as sex chromosomes. There are two  types of sex chromosomes “ x” and “ y “. Every cell of a male has one “x” and one “ y”, whereas the pair of sex chromosomes in a female has two “ x “ chromosomes. During fertilization, as sperm having “x” chromosomes or a “ y “ chromosomes fuses with an egg. The fertilized egg will have “x x “chromosomes. This zygote with “xx” chromosome will develop into a baby girl. If a sperm having “y” chromosomes, fuses with an egg “ x” then the fertilized egg has “x y “ chromosomes. This zygote with “x y “ sex chromosomes will develop into a baby boy.

light

Q1) if the angle of incidence formed on a plane mirror is 63 , what will be the measure of the angle of reflection?

Ans: According to the second law of reflection, if the angle of incidence is 63, then the angle of reflection will be 63.

Q2) How will the light falling on a surface of plane mirror travel?

Ans:  when a beam of light strike a smooth surface like that of a mirror, the rays are reflected . the reflected rays are also parallel to each other.

Q3) how will the light falling on a rough surface of a rock travel?

Ans: The parallel rays of light after striking a rough surface scatter in different directions.

Q4) Define refraction ?

Ans: The path of light changes as it passes from one medium to another. The path of the ray bends. This is known as refraction.

Q5) what is dispersion of light?

Ans: The splitting of white light into its components colours is called dispersion of light.

Q6) On which layer of the human eye is the image formed?

Ans: The image is formed on the retina

Q7) where in the human eye is the aqueous humor found?

Ans: Between the cornea and the iris is a liquid called the aqueous humor.

Q8) what type of lens is used to correct the defect of nearsightedness?

Ans: Concave lens.

Q9) explain reflection of light?

Ans: When light bounces after striking a surface, we say the light has reflected. This known as reflection of light.

Q10) what is the point of incidence?

Ans: The point at which the incident ray strikes the reflecting surface is called point of incidence.

Q11) what is virtual image?

Ans: The image which is not formed by actual rays of light , it cannot be captured on a screen. Such an image is known as a virtual image.

Q12) Differentiate between regular and irregular reflection.

Ans: When a beam of light strikes a smooth surface like that of a mirror, the rays are reflected. The reflected rays are also parallel to each other. Such a reflection is called specular  or regular reflection.

The parallel rays of light after striking a rough surface scatter in different directions, this type of reflection is known As diffuse or irregular reflection.

Q13) List any two features of an image formed by a plane mirror.

Ans: The image is upright and virtual

·       The image is laterally inverted.

Q14) List the three layers of human eye?

Ans: The human eye has three layers:

 The outer most sclera, chroid and the inner retina.

Q15) Explain the first law of reflection with a diagram?

Ans: The incident ray, the normal drawn at the point of incident and the reflected ray all lie in the same plane.

Q16) how is an image in a plane mirror?

Ans:  When light rays from an object fall on the surface of the plane mirror, they get reflected back. These reflected rays meet at a point when extended backward, the image is formed at this point. As the image is not formed by actual rays of light, it cannot be captured on a screen, such an image is known as a virtual image.

Q17) what is farsightedness? How can it be corrected?

Ans: A person with farsightedness ( hyperopia) has difficulty seeing objects that are near , this is because the light rays from a closer distance become focused behind the retina, this is caused by an eye ball that is too short.

This is corrected with a convex lens, which converges light and focuses it on the retina.

Q18) list the causes of blindness. Explain any one of them?

Ans: As a person ages, the eye sight is affected , most often the retina degenerates. As a result, the person has blurred vision and has difficulty in reading.

-      Diabetes, Cataract and Glaucoma are other causes of blindness in elderly people.

Glaucoma is a condition in which the pressure within the eye is increased due to an excess of aqueous humor liquid. It occurs in elderly people and can be managed with medicines and surgery.

  

Chemical effects of electric current

Q1) What is an atom?

Ans:An atom is an extremely small particle. It is made up of protons, neutrons, and electrons.

Q2) Differentiate between protons and electrons?

Ans:Protons are positively charged while neutrons do not have any charge. Electrons are presented in the space surrounding the nucleus of the atom. Electrons are negatively charged.

Q3) What is an anion?

Ans:Anions are negatively charged ions.

Q4) What charge does a cation carry?

Ans:Cations are positively charged ions.

Q5) Define ionization?

Ans: Ionisation is the process by which molecules break into cations and anions.

Q6) Give an example of an electrolytes?

Ans:Hydrochloric acid, sulphuric acid

Q7) Name a strong and a weak electrolyte.

Ans:Strong electrolyte: Nitric acid

Weak electrolyte: phosphoric acid

Q8) name the two electrodes in an elcetrolyte cell 

Ans: Anode and cathode

Q9) what is electrolysis?

Ans: The chemical change induced by the passage of electric current through electrolyte is known as electrolysis.

Q10) Mention one use of electroplating.

Ans: The purpose of electroplating is to coat a metal having a certain desired property such as wear resistance, corrosion protection, lubrication and aesthetic appeal .

Q11) Differentiate between anode and cathode?

Ans: The electrode connected to the positive terminal is the anode (positive electrode) and the electrode connected to negative terminal is the cathode.

Q12) what are conductors and insulators?

Ans: Some materials allow electricity to pass through them. Such materials are called conductors.

Materials that do not allow electricity to flow through them , such materials are called nonconductors of electricity or insulators.

Q13) What happens to common salt when it dissolves in water?

Ans: When table salt ( NaCl) dissolves in water, its molecules break into sodium ions and chloride ions. The sodium ions carry positive electric charge and the chloride ions carry negative electric charge.

Q14) why glucose a non-electrolysis?

Ans: Glucose and alcohol dissolve in water but do not form ions. Such compounds are called non-electrolysis.

All solutions that do not form ions do not conduct electricity.

Q15) why is sulphuric acid called an electrolyte?

Ans: A strong electrolyte is a compound such as Sulphuric acid that when dissolved in water ionizes completely. All its molecules break down to form cation and anions. Strong electrolytes are good conductor of electricity.

Q16) what is electroplating?

Ans: Electroplating is the process of deposition of a layer of one metal on top of another with the help of electric current.

Q17) Draw a labelled diagram to show that hydrochloric acid forms a strong electrolyte.

Ans:

Q18) Explain electrolysis of NaCl?

Ans: When table salt ( NaCl) dissolves in water, its molecules break into sodium ions ( Na⁺) and chloride ions ( Cl ^-) . the sodium ions carry positive electric charge and the chloride ions carry negative electric charge.

When a solution containing ions is subjected to electric current, the ions move . it is due to the movement of the ions that electric current flows through the solution. Thus ions conduct electric current through the solution. The more the number of ions present, the more the current that can be carried. Compounds such as common salt that dissolve in water and separate into ions, allow the conduction of electricity through the solution.

Q19) Explain with a suitable example the electroplating of a metal object.

Ans: The metal object which is to be electroplating is fixed in an electroplating chamber at the cathode.

The metal that is to be coated is made the anode. The chamber is then filled with an electrolyte which is generally the salt of the metal to be plated.

For example, in copper plating , a pure copper piece is fixed at the anode, the object to be plated with copper is fixed at the cathode and copper sulphat solution used as the electrolyte.

When the electric supply is switched on, the copper plate at the anode releases positively charged copper ions.

The copper ions move from the anode to the cathode through the solution and deposit on the metal object at the cathode. In copper electroplating, the electrolyte, copper sulphate solution remains unchanged.

Q20) Draw a labelled diagram of an electrolytic cell

The role of the police and that of the court

Q1) What is a First Information Report ( FIR)?

Ans: When a person becomes a victim or witness of a crime, he or she should file a First Information Report at the police station. The police will begin to investigate in the offence only after FIR has been lodged.

Q2) who is a public prosecutor?

Ans: Any criminal offence is deemed to be an offence against the society and therefore against the state. A public prosecutor is a lawyer who fights for or defends the state. He or she is appointed by the state.

Q3) on the basis of what factor does the judge decide a case?

Ans: The judge hears both the lawyers of the case. Then based on the evidences or proofs presented by the police, witnesses, defendant lawyer and prosecutor, the judge gives his or her verdict.

Q4) Describe the procedure to file an FIR?

Ans:The police station is required to register an FIR whenever information is given that a crime has been committed in order to avoid. The police must file an FIR and then transferred to the case to the concerned police station.

The FIR must be hand written, signed and prepared in duplicate. The FIR should specify the place, date and time of the incident.

Q5) Why should every accused be held innocent until proved otherwise? What will happen if this is not so?

Ans:Every accused is held innocent till proven guilty by a court of law. Therefore it is a fair and open trail is mandatory. Witnesses will be cross examined by both the lawyer and the prosecutor. Only if the public prosecutor proves guilty beyond doubt the verdict can be given, otherwise innocent people could be punished.

Q6) Explain the process of investigating crimes.

Ans:one of the most important duties of the police is to investigate crimes that have been committed.

    ·       Any crime committed in an area has to be reported at the police station concerned.

    ·       The officer of the police station has to register a First Information Report ( FIR) whenever information is given.

    ·       Even if the crime committed is not within the purview of the concerned police station, it must be registered in order to avoid unwanted delay, the officer there must file an FIR, the case can later be transferred to the police station concerned..

    ·       The police cannot decide the guilty of the accused – that is the work of the judiciary.