The shape of guard cells changes due to change in the:
protein composition of cells.
temperature of cells.
amount of water in cells.
position of nucleus in cells.
(3)
The amount of water in guard cells causes change in their shape. When water enters into the guard cell, it causes the stomatal pore to open. Similarly, if the guard cells shrink as a result of water loss, the pore closes.
Which of the following statements are true?
(i) Sudden action in response to something in the environment is called reflex action.
(ii) The path through which signals are transmitted from a receptor to a muscle or a gland is called reflex arc.
(iii) Motor neurons carry signals from spinal cord to effector organs.
(iv) Sensory neurons carry impulses from effectors to receptors.
(i) and (ii)
(iii) and (iv)
(i) and (iv)
(i), (ii) and (iii)
(3)
Statements (ii) and (iii) are wrong in their sense because sensory neurons carry signals from receptors to spinal cord and motor neurons carry signals from spinal cord to the muscles. Thus, statement (i) and (iv) are true
Which of the following is a plant hormone?
Insulin
Thyroxine
Oestrogen
Cytokinin
(4)
Cytokinin is a plant hormone that playe an important role in plant growth and development In plants, it aids embryogenesis, ell division chloroplast differentiation, and a variety of other processes
Cretinism results due to:
excess secretion of growth hormone.
under secretion of thyroxine.
excess secretion of adrenaline.
under secretion of growth hormone.
(2)
Cretinism is a condition arising from the deficiency of thyroid hormone, which causes stunted physical and mental growth. This deficiency, particularly during infancy or childhood, leads to reduced secretion of thyroxine (T4) hormone, which is critical for normal development. It is not related to the secretion levels of growth hormone or adrenaline but specifically to thyroxine produced by the thyroid gland.
The brain is responsible for:
thinking
regulating the heart beat
balancing the body
all of the above
(4)
The cerebellum of the brain is involved in muscle coordination, muscle tone, and balance. The medulla oblongata regulates heartbeat and controls consciousness and arousal. The cerebrum is the centre of brain for higher-order thinking functions such as learning, memory, language, and speech.
Involuntary actions in the body are controlled by:
Medulla in fore brain
Medulla in mid brain
Medulla in hind brain
Medulla in spinal cord
(3)
The involuntary activities are controlled by the medulla oblongata in the hind brain. Involuntary movements have a slower speed than voluntary movements. The beating of the human heart is the best example of this.
Which one of the following pairs of brain part and its functions is not correctly matched?
Pons – Consciousness
Cerebrum – Memory and intelligence
Cerebellum – Balance and posture
Medulla Oblongata – Involuntary activities
(1)
Pons is involved in respiratory control, communication between different areas of the brain, and perceptions including hearing, taste, and balance, but not in overall consciousness. The brain stem controls consciousness.
In humans, the life processes are controlled and regulated by:
Reproductive and endocrine systems
Respiratory and nervous systems
Endocrine and digestive systems
Nervous and endocrine systems
(4)
The nervous and endocrine systems in humans work together to control and coordinate all activities. Both of these systems are made up of a number of organs that work in coordinated manner.
Choose the incorrect statement about insulin.
It is produced from pancreas.
It regulates growth and development of the body.
It regulates blood sugar level.
Insufficient secretion of insulin will cause diabetes.
(2)
Growth hormone is a peptide hormone that promotes growth, cell reproduction, and regeneration. Insulin is made in the pancreas by beta cells found in the Islets of Langerhans. It is essential for the absorption of blood sugar by the cells. Along with glucagon, it regulates blood sugar levels.
Select the mismatched pair.
Adrenaline : Pituitary gland
Testosterone : Testes
Estrogen : Ovary
Thyroxine : Thyroid gland
(1)
The adrenal glands produce adrenaline, which activates the body’s fight-or-flight response. The testes, which are responsible for the development of male sexual traits, produce testosterone. The ovaries, which are responsible for the development of female sexual traits, produce oestrogen. Thyroxine is a hormone generated by the thyroid gland to accelerate the production of oxidative metabolism in cells.
