Biology
The diagram given below is a representation of a certain phenomenon pertaining to the nervous system. Study the diagram and answer the following questions:
(i) Name the phenomenon which is being depicted.
(ii) Give the technical term for the point of contact between the two nerve cells.
(iii) Name the parts 1, 2, 3 and 4.
(iv) Write the functions of parts 5 and 6.
(v) How does the arrangement of neurons in the spinal cord differ from that of the brain?
Answer
(i) The phenomenon that is depicted here is the reflex action.
(ii) The term for the point of contact between the two nerve cells is called the Synapse.
(iii) The parts 1, 2, 3 and 4 are:
- 1 → Sensory / Afferent neuron
- 2 → Dorsal ganglion / Dorsal root
- 3 → White matter
- 4 → Grey matter
(iv) Below are the functions of parts 5 and 6:
- The function of 5 (Synapse) — It transmits the sensory impulse from sensory neurons to the motor neurons.
- The function of 6 (Motor neuron / Efferent neuron) — It transmits the command to the effectors part (e.g. muscles).
(v) The arrangement of neurons in the spinal cord differs from that of the brain. In the brain, Gray matter is present on the outside and white matter on the inner side. In Spinal cord, white matter is present on the outside and Gray matter on the inner side.
Related Questions
A candidate in order to study the process of osmosis has taken 3 potato cubes and put them in 3 different beakers containing 3 different solutions. After 24 hours, in the first beaker the potato cube increased in size, in the second beaker the potato cube decreased in size and in the third beaker there was no change in the size of the potato cube. The following diagram shows the result of the same experiment:
(i) Give the technical terms of the solutions used in beakers 1, 2 and 3.
(ii) In beaker 3, the size of the potato cube remains the same. Explain the reason in brief.
(iii) Write the specific feature of the cell sap of root hairs which helps in absorption of water.
(iv) What is osmosis?
(v) How does a cell wall and a cell membrane differ in their permeability?
A potted plant was taken in order to prove a factor necessary for photosynthesis. The potted plant was kept in the dark for 24 hours. One of the leaves was covered with black paper in the centre. The potted plant was then placed in sunlight for a few hours.
(i) What aspect of photosynthesis was being tested?
(ii) Why was the plant placed in the dark before beginning the experiment?
(iii) During the starch test, why was the leaf (1) boiled in water (2) boiled in methylated spirit.
(iv) Write a balanced chemical equation to represent the process of photosynthesis.
(v) Draw a neat diagram of a chloroplast and label its parts.
Give scientific reasons for the following statements:
(i) Use of CFC is banned in many countries.
(ii) We cannot distinguish colours in moonlight.
(iii) Balsam plants wilt during mid-day even if the soil is well watered.
(iv) Carbon monoxide is highly dangerous when inhaled.
(v) A person after consuming alcohol walks clumsily.
Given below is a diagram representing a stage during mitotic cell division. Study it carefully and answer the questions which follow:
(i) Is it a plant cell or an animal cell? Give a reason to support your answer.
(ii) Identify the stage shown.
(iii) Name the stage which follows the one shown here. How is that stage identified?
(iv) How will you differentiate between mitosis and meiosis on the basis of the chromosome number in the daughter cells?
(v) Draw a duplicated chromosome and label its parts.