How do Organisms Reproduce? — Science STD 10 — Question

Consider the following food chains:

1. Plants → Mice → Snakes → Hawks
2. Plants → Mice → Hawks

If energy available at the producer level in both the food chains is 100J, in which case will hawks get more energy as food and by how much? Justify your answer.

A cylindrical structure P in our body begins in continuation with medulla and extends downwards. It is enclosed in a bony cage Q and surrounded by membranes R. As many as x pairs of nerves arise from the structure P. The structure P is involved in the reflex actions of our body and conduction of nerve impulses to and from another organ S of our body with which it forms CNS.

1. Name the structure P.
2. Name (i) bony cage Q, and (ii) membranes R.
3. How much is x?
4. Name the organs S.
5. What are the reflexes involving structure P only known as?

How do Mendel’s experiments show that traits are inherited independently?

Why are environmentalists insisting upon sustainable natural resource management? Give reasons.

Draw a labelled diagram of the human male reproductive system. With the help of this diagram, describe the working of human male reproductive system?

There are two similar glands P which are located on top of two similar organs Q in the human body. P are often called the emergency glands and they secrete a hormone R into the blood stream. R is secreted in large amounts when a person is frightened. It brings about temporary changes in the body which allow a lot of substance S from the liver to go into the blood to provide a lot of energy in a very short time. This helps a person to fight back or run away from the frightening situation.
What are P, Q, R and S?

The organs P and Q of two animals have different structures but similar functions. On the other hand, the two organs R and S of two other animals have the same basic structure but different functions.

1. What are the organs like P and Q known as?
2. Name the organs like P and Q. Also name the animals which have such organs.
3. What are the organs like R and S called?
4. Name the organs like R and S. Also name the animals which have such organs.

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.

Draw the structure of a neuron and explain its function.