Life Processes — Science STD 10 — Question

Explain the phenomenon of electromagnetic induction. Describe an experiment to show that a current is set up in a closed loop when an external magnetic field passing through the loop increases or decreases.

When we touch a hot plate unknowingly, then this heat is sensed by a receptor P present in our fingers. The receptor triggers and impulse in neuron Q which transmits the message to an organ R which is a part of the central nervous system. Here the impulse is passed on to a neuron S which in turn passes it to a yet another neuron T. The neuron T passes the impulse to a tissue U in our arm. The tissue U then contracts and pulls our hand away from the hot plate.

1. What is the name of (i) receptor P (ii) neuron Q, and (iii) organ R?
2. What is (i) neuron S, and (ii) neuron T?
3. Name the tissue U.
4. What name is given to the phenomenon in which hand is pulled away quickly from the hot plate?
5. Name the effector in this whole process.

An element X (atomic number 17) reacts with an element Y (atomic number 20) to form a divalent halide.

1. Where in the periodic table are elements X and Y placed?
2. Classify X and Y as metal (s), non-metal (s) or metalloid (s)
3. What will be the nature of oxide of element Y? Identify the nature of bonding in the compound formed.
4. Draw the electron dot structure of the divalent halide.

(i) "Keerthi thinks that Substitution reaction occurs in saturated Hydrocarbons, on the contrary Krishi thinks, it occurs in unsaturated Hydrocarbons." Justify with valid reasoning whose thinking is correct.
(ii) "Methane and Propane and their Isomers are used as fuels" Comment. Draw the electron dot structure of the immediate lower homologue of Propane. Give any two characteristics of homologues of a given homologous series.
(iii) A mixture of oxygen and ethyne is burnt for welding. Can you predict why a mixture of ethyne and air is not used?

The following diagram shows a part of the periodic table containing first three periods in which five elements have been represented by the letters a, b, c, d and e (which are not their chemical symbols):

1. Select the letter which represents an alkali metal.
2. Select the letter which represents a noble gas.
3. Select the letter which represents a halogen.
4. What type of bond is formed between a and e?
5. What type of bond is formed between d and e?

For a heater rated at 4kW and 220V, calculate:

1. The current,
2. The resistance of the heater,
3. The energy consumed in 2 hours, and
4. The cost if 1kWh is priced at ₹60.

In the following schematic diagram for the preparation of hydrogen gas as shown in Figure, what would happen if following changes are made?

1. In place of zinc granules, same amount of zinc dust is taken in the test tube.
2. Instead of dilute sulphuric acid, dilute hydrochloric acid is taken.
3. In place of zinc, copper turnings are taken.
4. Sodium hydroxide is taken in place of dilute sulphuric acid and the tube is heated.

What is biomass? Explain the principle and working of a biogas plant using a labelled schematic diagram.

A and B are two pairs of glands that are present in the human endocrine system. The pair A is found only in females, whereas B is present only in males. Glands A make and secrete two hormones C and D, whereas glands B make and secrete only one hormone E. In addition to hormones, Glands A make gametes F, whereas glands B make gametes G.

1. What are the glands A?
2. What are the hormones C and D?
3. What are the glands B? Name the hormone E.
4. What are the gametes F and G?
5. Which event in the life of males and females is associated with the secretion of the hormones C, D and E?

What are the methods used by plants to get rid of their waste products?