Control and Coordination — Science STD 10 — Question

Mendeleev predicted the existence of certain elements not known at that time and named two of them as Eka-silicon and Eka-aluminium.

1. Name the elements which have taken the place of these elements.
2. Mention the group and the period of these elements in the Modern Periodic Table.
3. Classify these elements as metals, non-metals or metalloids.
4. How many valence electrons are present in each one of them?

When a female child is born, her ovaries already contain thousands of immature eggs (or ova) contained in immature structures A. On maturing, A bursts open and an egg shoots out of the ovary in a process called B. The process B starts in the females at puberty and occurs again and again after a time period x. Before every occurrence of process B, the inner lining of uterus becomes thick and soft with lots of blood vessels in it. When the egg cell gets fertilised by a sperm, then an event C occurs in the life of mature human female which lasts for time period y leading to the birth of baby. If, however, the egg cell released by the ovary does not get a sperm to fuse with, then the thick and soft inner lining of uterus breaks down and comes out of the female's body in an event called D. The occurrence of event D is controlled by chemical substances E.

1. What are A?
2. What is process B?
3. What is the time period x?
4. Name the event C.
5. How much is the time period y?
6. What is the name of process D?
7. Name the chemical substances E.

Describe the structure of diamond. Draw a simple diagram to show the arrangement of carbon atoms in diamond.

Every household produces a lot of material A daily. In one of the methods of disposal B, material A is burned at a very high temperature of about 1000°C in a structure called C. During this process, the organic matter present is removed as D and E whereas F is left behind (which can be dumped in a landfill site).

1. What is material A?
2. Name the method of disposal B.
3. What is structure C known as?
4. What are (i) D (ii) E, and (iii) F?
5. This method is especially suitable for the disposal of materials produced by certain institutions. Name such institutions.

Draw a labelled diagram of the human respiratory system.

Describe the activity that shows that a current-carrying conductor experiences a force perpendicular to its length and the external magnetic field. How does Fleming’s left-hand rule help us to find the direction of the force acting on the current carrying conductor?

What are the different types of tropisms? Define each type of tropism. Write the name of stimulus in each case.

What is meant by ‘rusting of iron’? With the help of labelled diagrams, describe an activity to find out the conditions under which iron rusts.

With a schematic diagram, explain the overall process of respiration.