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Test Paper

Test Paper 2

Class 8 - Living Science Biology Ratna Sagar


Fill in the blanks

Question 1

The membranes enveloping the brain are called ............... .

Answer

The membranes enveloping the brain are called meninges.

Question 2

The message that travels along a nerve in the form of a wave of chemical disturbance is called ............... .

Answer

The message that travels along a nerve in the form of a wave of chemical disturbance is called impulse.

Question 3

Endocrine glands are also called ............... glands because they do not have their own duct.

Answer

Endocrine glands are also called ductless glands because they do not have their own duct.

Question 4

The hormone thyroxine is released by ............... gland.

Answer

The hormone thyroxine is released by thyroid gland.

Question 5

............... vaccine is given to children as a preventive measure against tuberculosis.

Answer

BCG vaccine is given to children as a preventive measure against tuberculosis.

Question 6

The process of treating animal skin to produce leather is called ............... .

Answer

The process of treating animal skin to produce leather is called tanning.

Question 7

The breeding and management of silkworms for the production of silk is called ............... .

Answer

The breeding and management of silkworms for the production of silk is called sericulture.

Write true or false. Correct the false statement.

Question 1

Motor nerves carry impulses from the sense organs to the spinal cord.

Answer

False

Corrected statement — Motor nerves carry impulses from the spinal cord to the sense organs.

Question 2

Under-secretion of growth hormones may lead to a condition called dwarfism.

Answer

True

Question 3

The chemicals secreted by exocrine glands are called hormones.

Answer

False

Corrected statement — The chemicals secreted by endocrine glands are called hormones.

Question 4

Bites of poisonous snakes can only be treated with anti-venom serum.

Answer

True

Question 5

Communicable diseases are also called congenital diseases.

Answer

False

Corrected statement — Communicable diseases are also called infectious diseases.

Question 6

A fracture is a crack in the bone which requires immediate medical attention.

Answer

True

Question 7

The place where bees are cultured and bred to get commercial products is called apiary.

Answer

True

Differentiate between

Question 1

cerebrum and cerebellum

Answer

Sl.
No.
cerebrumcerebellum
1.It is the uppermost, largest and the most prominent part of the brain.It is a small, egg-shaped lobe located at the base under the cerebrum.
2.It is highly convoluted in appearance with ridges and grooves.It does not have convolutions, but has many furrows.
3.It controls mental activities such as thinking and reasoning, memory, intelligence and perception of taste, pain and touch etc.It coordinates the movement of voluntary muscles and maintains the balance of the body.

Question 2

endocrine and exocrine glands

Answer

Sl.
No.
Endocrine glandsExocrine glands
1.Endocrine glands are specialized glands which release their secretions directly into cells or the surrounding tissue.Exocrine glands are glands which release their secretions through ducts to the target organ.
2.Endocrine glands are ductless glands.Exocrine glands are glands with ducts.
3.Endocrine glands secrete hormones.Exocrine glands secrete enzymes.
4.Response time is slower since the secretion has to be carried through blood.Response time is fast since the secretion is carried through ducts.
5.They control long term activities of the target organ.They control short term activity.
6.Examples are: Pituitary gland and thyroid glandExamples are: Salivary glands and sweat glands

Question 3

sensory nerves and mixed nerves

Answer

Sl.
No.
Sensory nervesMixed nerves
1.Sensory nerves are the nerves that carry messages from the sense organs to either the spinal cord or the brain.Mixed nerves perform the function of both sensory nerves and motor nerves. They transmit messages from the central nervous system to the muscles of the body.
2.They contain only sensory fibres.They contain sensory fibres as well as motor fibres.
3.For example, the optic nerve that sends messages from the eye to the brain is a sensory nerve.For example, the nerve that transmits messages to the tongue is a mixed nerve.

Question 4

vaccination and immunization

Answer

Sl.
No.
VaccinationImmunization
1.Administration of a weakened or inactive pathogen (a vaccine) to stimulate the immune system to develop resistance against that pathogen is called vaccination. A vaccine can be injected or taken orally.The process by which a person is made resistant or immune against a particular disease by administering a vaccine is called immunization.
2.It is the process of administering vaccine. A vaccine may not always guarantee immunity.It is the process of making a person immune to a particular disease.

Question 5

being healthy and being disease free

Answer

Sl.
No.
Being healthyBeing disease-free
1.State of physical, mental and social well-being.State of body without having any discomfort or symptoms of a disease.
2.A healthy person is always energetic and disease-free.A disease-free person may not necessarily be healthy or energetic.

Question 6

sericulture and apiculture

Answer

Sl.
No.
SericultureApiculture
1.The breeding and management of silk worm for the production of silk is called sericulture.The breeding and management of honeybees for commercial purpose is called apiculture.
2.It is done for Silk.It is done for Honey and Beeswax.

Give reasons for the following

Question 1

Increased levels of thyroxine in the body leads to weight loss.

Answer

Increased level of thyroxine due to over secretion increases rate of metabolism and cellular respiration. This causes weight loss.

Question 2

Animals are beneficial to us in many ways.

Answer

We get a variety of products from animals. Animals are beneficial to us in following ways:

  1. They provide us milk, meat and eggs.
  2. We can use the drought animals for work in field.
  3. They also provide us wool, hide, leather etc.
  4. Other products like honey, silk, pearl and lac are derived from animals.

Answer the following in detail.

Question 1

Describe the structure of a neuron with the help of a diagram.

Answer

A neuron is the longest cell of our body. It has three parts — cell body, axon and dendrites.

  1. The cell body called cyton contains the nucleus.
  2. Many short fibres called dendrons arise from the cell. They further divide to form dendrites. Dendrites receive messages from other neurons.
  3. A single, long fibre called axon extends from the other side of the cell body. It is covered by a sheath called myelin sheath.

Below diagram shows the structure of a neuron:

Explain the structure of a motor nerve cell with the help of a diagram. Nervous System in Humans, Living Science Biology Ratna Sagar Solutions ICSE Class 8.

Question 2

Explain reflex action with the help of an example.

Answer

An automatic, spontaneous and mechanical response to a stimulus; controlled by the spinal cord without the involvement of the brain is called a reflex action.
For example, if we step on a sharp object, we instantly withdraw our foot. This reaction is automatic and does not involve thinking about it.

Question 3

Describe the various physical changes that occur during adolescence.

Answer

The various physical changes that occur during adolescence are:

  1. Sexual maturation — In males testes start producing testosterone and sperms. In females, the ovaries start releasing eggs and produce the female hormones, oestrogen and progesterone. Sex organs develop fully and secondary sexual characteristics like enlargement of external genital organs in males and enlargement of breasts in females also start.
  2. Increase in height — There is a spurt in growth hormone leading to sudden increase in height due to the elongation of the bones of the legs and arms. Age by which full height is attained is 14 to 15 years for girls and 18 to 19 years for boys.
  3. Change in body appearance — In males, the shoulders become broad and the chest becomes wide.The muscles also grow and develop more than in girls. In females, there is widening of the pelvic region and broadening of the hips. The breasts also develop and enlarge in size. Also in both males and females, hair starts growing in the armpit and pubic area. In males, facial hair (as beard and mustache) grows.
  4. Change in voice — There is growth in the voice box or larynx. It grows more in males than in females. As a result, males develop deep voice whereas females develop a high-pitched voice.

Question 4

What is HIV? How is it different from AIDS? Can HIV be prevented?

Answer

HIV stands for Human Immuno-deficiency Virus. It is a virus which causes AIDS. AIDS stands for Acquired Immuno deficiency Syndrome.
The difference between HIV and AIDS is that HIV is a virus which acts as the vector or causative agent for the disease that is called AIDS.

Following are the ways to prevent AIDS:

  1. Screening of blood before transfusion
  2. Avoiding sharing and reuse of blades, needles and syringes and surgical instruments.
  3. Avoiding pregnancy if mother is HIV positive
  4. Safe sex
  5. Educating people

Question 5

List five ways in which fungi help mankind.

Answer

Five ways in which fungi help us are:

  1. They decompose the dead, decaying bodies of plants and animals. Fungi also helps in making the soil fertile.
  2. Morels and some mushrooms are consumed as delicacies.
  3. Yeast is used in baking industry.
  4. Alcohol and alcoholic drinks are produced by the fermentation of grapes, barley etc. by yeast.
  5. Yeast is also used for manufacturing vitamins. Penicillin, an antibiotic, is obtained from Penicillium, a fungi.

Label the parts

Question 1

Label the parts of the human brain marked a to c.

Label the parts of the human brain marked a to c. Test Paper, Living Science Biology Ratna Sagar Solutions ICSE Class 8.

Answer

The labelled parts of brain are:

a → Cerebrum

b → Cerebellum

c → Medulla Oblongata

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