Section A (10 Marks)
The mineral element in haemoglobin :
Reason — Iron forms the prosthetic group i.e haemin which combines with globin protein to form haemoglobin.
The number of cranial nerves in humans are :
- 31 pairs
- 12 pairs
Reason — The cranial nerves are a set of 12 paired nerves in the back of the brain.
Gigantism and Acromegaly are due to:
- Hypersecretion of Growth hormone
- Hypersecretion of Thyroxine
- Hyposecretion of Growth hormone
- Hyposecretion of Thyroxine
Hypersecretion of Growth hormone
Reason — Acromegaly and Gigantism are disorder in adults in which the pituitary gland produces too much of Growth hormone.
Pericardium covers the
- Spinal cord
Reason — Pericardium is a double walled membranous bag, enclosing the human heart.
The circular opening in the centre of iris :
Reason — Pupil is a small opening in the center of the iris, through which the light enters into the eye.
The blood vessel that carries oxygenated blood is :
- Pulmonary artery
- Pulmonary vein
- Renal vein
- Hepatic vein
Reason — The pulmonary veins carry oxygenated blood from the lungs to the left atrium.
Organ of corti is present inside the :
- Semicircular canals
Reason — The Organ of corti is present in the cochlea. It is a structure present on the basilar membrane. It contains hair cells that act as auditory receptors.
The structure that stores urine temporarily is :
- Urinary bladder
Reason — The urine formed in kidneys is taken by ureters to urinary bladder where it is temporarily stored.
Islets of Langerhans are located in
- Pituitary gland
Reason — Islets of Langerhans are endocrine cells present in Pancreas. They have three type of cells alpha, beta and gamma cells.
The main nitrogenous waste formed in the human body :
- Uric acid
Reason — Urea forms the main nitrogenous waste in human body.
Section B (30 Marks)
Simple goitre is usually seen in people living in the hilly regions. Give two reasons for the statement.
Simple goitre is usually seen in people living in the hilly regions because:
- Iodine is deficient in soil of hilly regions and hence in the food grown there.
- Iodine is also deficient in drinking water available in the hilly regions which is obtained from rivers and streams fed by melting snow.
What are the two types of blood circulation in humans?
The two types of blood circulation in humans are:
- Pulmonary circulation
- Systemic circulation
Mention the three major steps involved in the production of urine.
The three major steps involved in the production of urine are:
Draw a neat diagram of a Neuron and label any two parts.
Diagram of Neuron with Cyton and Axon labelled is shown below:
What is Adrenal Virilism? What causes this condition?
The overgrowth of adrenal cortex in a mature woman leads to the development of certain male characteristics in her such as a beard, a moustache and deep male voice. This condition is known as Adrenal Virilism.
It caused due to the oversecretion of sex corticoids (adrenal androgens).
Which is the light sensitive layer of the eyeball? Where exactly is the image formed on this layer?
Retina is the light sensitive layer of the eyeball. Image is formed on retina.
Study the diagram given below and answer the questions that follow :
(a) Identify the defect of the eye by mentioning the technical term.
(b) Mention one reason for this defect.
(c) Name the type of lens used to correct this defect.
(b) Lens is too flat.
(c) Convex lens.
Give the biological terms for the three tiny bones present in the middle ear.
Malleus, Incus and Stapes.
Name the endocrine gland that secretes Thyroxine. Give any one function of Thyroxine.
Thyroid gland secretes thyroxine.
One function of thyroxine — It regulates the basal metabolism, i.e., the rate of cellular oxidation resulting in heat production at rest.
Give the full form of the abbreviation ACTH. Which gland secretes this hormone?
It is secreted by pituitary gland.
Define the term Synapse. How are Cytons and Axons of neurons placed in the Cerebrum?
Synapse is the point of contact between the terminal branches of the axon of a neuron with the dendrites of another neuron separated by a fine gap.
In the Cerebrum, Cytons are present in the outer portion (cortex) constituting the gray matter and Axons are present in the inner portion constituting the white matter.
Name the three membranous coverings of the human brain.
- Dura mater (outer layer)
- Arachnoid (middle layer)
- Pia mater (inner layer).
Name the nerve that transmits impulses to the brain from :
(a) Auditory nerve
(b) Optic nerve
A mature mammalian erythrocyte lacks nucleus and mitochondria but is efficient in its functioning. Explain by giving suitable reasons.
Lack of nucleus and mitochondria helps erythrocytes in the following ways:
- Loss of nucleus makes the red cells biconcave, thus increasing their surface area to absorb more oxygen.
- Loss of mitochondria means that they cannot use the absorbed oxygen themselves.
The diagram given below is that of a human brain. Answer the questions that follow :
(a) Label the parts numbered 2 and 3.
(b) State any one function of the part numbered 1.
(a) Parts numbered 2 and 3 are:
- 2 → Cerebellum
- 3 → Medulla oblongata
(b) The part labelled as 1 is Cerebrum. It is the seat of intelligence, consciousness and will-power. It controls all voluntary actions.
What is a reflex action? Name the two types of reflexes.
Reflex action is an automatic/quick/immediate, involuntary action in the body brought about by a stimulus. The two types of reflexes are natural reflexes and conditioned reflexes.
Give the exact location of Pulmonary semilunar valve. When does it close?
Pulmonary semilunar valves are located at the opening of the right ventricle into the pulmonary artery. It closes during the atrial systole phase of the cardiac cycle.
Name the hormones whose deficiency causes :
(a) Diabetes mellitus
(b) Diabetes insipidus
(a) Diabetes mellitus - Insulin
(b) Diabetes insipidus - Vasopressin
Draw a neat diagram of a longitudinal section of a human kidney and label Renal Cortex and Renal Medulla on the diagram.
Diagram showing longitudinal section of a human kidney with Renal Cortex and Renal Medulla labelled is shown below:
Mention one function for each of the following:
(a) Lymphocytes produce antibodies which kill or neutralise the germs or the poisons from them.
(b) Thrombocytes help to form blood clots in order to slow or stop bleeding and help wounds to heal.
(c) Neutrophils engulf bacterial and fungal pathogens through a process known as phagocytosis.