Q 11. (a) Name a metal for each case:
(i) It does not react with cold as well as hot water but reacts with steam.
(ii) It does not react with any physical state of water.
(b) When calcium metal is added to water, the gas evolved does not catch fire but the same gas evolved on adding sodium metal to water catches fire. Why is it so ?
Q 12. Name the system which facilitates communication between central nervous system and the other parts of the body. Mention two types of nerves it consists of along with their organs of origin.
11)i)Aluminium
ii)Gold
12)Peripheral Nervous System facilitates communication between Central Nervous System and other parts of the body.The two types of nerves it consists are - i)Cranial nerves from the brain, ii)Spinal nerves from the spinal cord.
13)In case of asexually reproducing organisms, mitosis is the method used for cell division and reproduction in cells. This process starts with one replication and one division of the chromosome material. The whole set of chromosomes is replicated and transferred to the next generation. This results in the chromosome numbers in the two cells produced, being the same as in the parent cell. Example: Reproduction in Amoeba by binary fission or Plasmodium by multiple fission.
Sexually reproducing organisms undergo meiosis wherein the chromosome number is halved to form gametes. In this way, the new offspring receives one set of chromosome from each parent. The gametes then fuse together to form the zygote which restores the diploid chromosome number in the newly formed offspring. Example: Reproduction in human beings where there are 46 chromosomes in a diploid individual. Each parent contributes 23 chromosomes in the form of gametes. The two gametes fuse to form the zygote which again has 46 chromosomes.
ii)Gold
12)Peripheral Nervous System facilitates communication between Central Nervous System and other parts of the body.The two types of nerves it consists are - i)Cranial nerves from the brain, ii)Spinal nerves from the spinal cord.
13)In case of asexually reproducing organisms, mitosis is the method used for cell division and reproduction in cells. This process starts with one replication and one division of the chromosome material. The whole set of chromosomes is replicated and transferred to the next generation. This results in the chromosome numbers in the two cells produced, being the same as in the parent cell. Example: Reproduction in Amoeba by binary fission or Plasmodium by multiple fission.
Sexually reproducing organisms undergo meiosis wherein the chromosome number is halved to form gametes. In this way, the new offspring receives one set of chromosome from each parent. The gametes then fuse together to form the zygote which restores the diploid chromosome number in the newly formed offspring. Example: Reproduction in human beings where there are 46 chromosomes in a diploid individual. Each parent contributes 23 chromosomes in the form of gametes. The two gametes fuse to form the zygote which again has 46 chromosomes.