This set of Biology Multiple Choice Questions & Answers (MCQs) focuses on “Neural Control and Coordination – Reflex Action and Reflex Arc”.
1. Which of the following is not stimulation for reflex action?
a) Hot object
c) Cold object
d) Scary animals
Explanation: The withdrawal of the body part can be due to our contact with extremely hot or cold objects, pointed objects, animals that are scary, or are poisonous.
2. What is a reflex action?
a) Action that flexes the body
b) Involuntary action in response to a peripheral nervous stimulation
c) Voluntary action in response to a peripheral nervous stimulation
d) Voluntary action that flexes our body
Explanation: A reflex action is an involuntary action taken by our body in response to peripheral nerve stimulation. This process does not require the conscious effort of our brain and it takes place instantly to save us from bearing any harm.
3. In a reflex action, the efferent neurons receive a signal from the CNS.
Explanation: The afferent neurons receive the signals from a sensory organ and transmits the impulse via a dorsal nerve root into the CNS and at the level of the spinal cord.
4. Which of the following forms a reflex arc?
a) Organ and tissue
b) Cells and neurons involved
c) Effort and load
d) Stimulus and response
Explanation: The efferent neurons carry the signals from the central nervous system to the effector organs. The stimulus and response thus form a reflex arc, for example; the knee jerk reflex.
5. Which of the following is not a function of sensory organs?
a) Detect all the changes in the environment
b) Send appropriate signals to CNS
c) Analysis of signals
d) Receive signals
Explanation: The sensory organs detect all types of changes in the environment and send appropriate signals to the CNS, where all the inputs are processed and analysed.
6. In which of the following, olfactory receptors are present?
Explanation: The nose contains mucus coated receptors that are specialised for receiving the sense of smell and are called olfactory receptors. These are made up of olfactory epithelium.
7. The olfactory epithelium consists of how many cells?
Explanation: Olfactory epithelium consists of three kinds of cells namely:
i. Basal cells
ii. Supporting cells
iii. Olfactory receptor cells
They get modified to form olfactory neurons.
8. The olfactory epithelium is the extension of which of the following?
b) Pituitary gland
c) Association areas
d) Limbic system
Explanation: The neurons of the olfactory epithelium extend from the outside environment directly into a pair of broad bean-sized organs, called olfactory bulb, which are extensions of the brain’s limbic system.
9. Which of the following has the gustatory receptors?
Explanation: The tongue detects taste through taste buds, containing gustatory receptors. With each taste of food or sip of a drink, the brain integrates the differential input from the taste buds and a complex flavour is perceived.
10. Both nose and tongue detect dissolved chemicals.
Explanation: Both nose and tongue detect dissolved chemicals. The chemical senses of gustation (taste) and olfactory (smell) are functionally similar and interrelated.
11. Where are our eyes located?
a) Zygomatic cavity
b) Vomer cavity
d) Sphenoid cavity
Explanation: Our paired eyes are located in sockets of the skull called orbits. The adult human eyeball is nearly a spherical structure. The wall of the eyeball is composed of three layers.
12. Which of the following layer forms the ciliary body?
c) Choroid layer
Explanation: The choroid layer is thin over the posterior two-thirds of the eyeball, but it becomes thick in the anterior part to form the ciliary body. The ciliary body itself continues forward to form a pigmented and opaque structure called the iris.
13. The diameter of the pupil is regulated by which of the following?
a) Muscle fibres of the iris
c) Choroid layer
d) Muscle fibres of the lens
Explanation: The diameter of the pupil is regulated by the muscle fibres of the iris. The eyeball contains a transparent crystalline lens which is held in place by the ligaments attached to the ciliary body.
14. How many layers of neural cells are present in the retina?
Explanation: The inner layer of the eye is retina and it contains three layers of neural cells which are:
i. Ganglion cells
ii. Bipolar cells
iii. Photoreceptor cells.
15. How many types of photoreceptor cells are present in the retina?
Explanation: There are two types of photoreceptor cells, namely, rods and cones. These cells contain the light-sensitive proteins called the photopigments. Daylight vision is the function of cones and twilight vision is the function of rods.
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