Science Part ii Solutions Solutions for Class 10 Science Chapter 3 - Life Processes In Living Organisms Part 2

Answer:

Answer:

a. In humans, sperm production occurs in the organ testes.
b. In humans, Y chromosome is responsible for maleness.
c. In male and female reproductive system of human, bulbourethral gland is same.
d. Implantation of embryo occurs in uterus.
e. Asexual type of reproduction occurs without fusion of gametes.
f. Body breaks up into several fragments and each fragment starts to live as a new individual. This is fragmentation type of reproduction.
g. Pollen grains are formed by meiotic division in locules of anthers.
 

Answer:

Growth of follicles present in the ovary occurs under the effect of follicle stimulating hormone. This follicle secretes estrogen. Endometrium of uterus grows/regenerates under the effect of estrogen. Under the effect of luteinizing hormone, fully grown up follicle bursts, ovulation occurs and corpus luteum is formed from remaining part of follicle. It secretes progesterone and estrogen. Under the effect of these hormones, glands of endometrium of uterus are activated and it becomes ready for implantation.

Answer:

a. Asexual reproduction in unicellular organisms can be of three types:

Binary fission: Binary fission is the splitting of parent organisms into two halves, each of which develops to form a complete daughter cell. For example, Amoeba reproduces asexually by the process of binary fission. In Amoeba,binary fission begins with the division of the nucleus. This is followed by the division of the cytoplasm and the cell. Each part receives a portion of the nucleus. Finally, two cells are formed from one parent Amoeba.

Answer:

Sexual reproduction involves the fusion of two types of gametes i.e., the male and the female gametes. The zygote formed contains a fusion of both the sperm nucleus and the egg nucleus. Due to this, the new individual has characteristics which are similar to both the parents while some characteristics which are different from both the parents. Thus, the new individual formed from sexual reproduction inherits the characteristics of both the parents. For example, if the father has black hair while the mother has brown hair, the chances are that their offspring may have either black or brown hair. 

Answer:

a. Human male reproductive system



b. Human female reproductive system



c. Flower with its sexual reproductive organs



d. Menstrual cycle


 

Answer:

a. Hormones related with male reproductive system- testosterone
b. Hormones secreted by ovary of female reproductive system- estrogen and progesterone
c. Types of twins- Monozygotic and dizygotic twins
d. Any two sexual diseases- AIDS and Gonorrhea
e. Methods of family planning- Oral pills, condoms, IUD's
 

Answer:

Human females have two X chromosomes (XX) and human males have one X and one Y chromosome (XY). Therefore, the eggs produced by females have only X chromosomes while the sperms produced by males can have either X or Y chromosome. If an unfertilised egg fuses with a sperm containing X chromosome, then it gives rise to a girl child having two X chromosomes. If an unfertilised egg fuses with a sperm containing Y chromosome, then it gives rise to a male child having one X and one Y chromosome.

Answer:

Asexual reproduction is the process by which a plant gives rise to a new plant without producing seeds or spores. Asexual reproduction in plants occur by vegetative propogation. The development of a new plant from the vegetative part of a plant like stem, root or leaf is known as vegetative propagation. The various methods of vegetative propogation are:

From underground stem: A potato plant has an underground stem known as the tuber. It has many buds called eyes. A vegetative bud consists of a short stem, around which immature overlapping leaves are present in a folded state. A bud can give rise to a new plant through asexual reproduction.

Rhizome: The underground stem of ginger is known as the rhizome which is capable of giving rise to a new plant. Corm is the underground stem as found in Gladiolus. It can also be used for vegetative propagation.

Through leaves: Leaves perform the function of photosynthesis. However, they can take part in asexual reproduction as well. In some plants, leaves can give rise to a new plant asexually. For example, the leaves of the plant Bryophyllum contain buds on its margins. These buds give rise to a new plant through asexual reproduction.

From aerial stem: In certain plants, a slender stem arises from the base of the plant and touches the soil, it develops roots and buds at the point of contact with the soil and gives rise to new plants. When the new plant is old enough the stem connecting it to the parent plant withers away.

Answer:

Many couples all over the world are unable to produce children because of various reasons like congenital diseases, drugs, immunological and psychological factors. Such couples can be assisted to have children through techniques called assisted reproductive technologies (ART).  IVF is one such ART and include the following techniques:
 

• ZIFT − It stands for zygote intra fallopian transfer. In ZIFT, the sperm from a donor male and the ova from a donor female are fused in the laboratory. The zygote so formed is transferred into the fallopian tube at the 8 blastomeres stage.
• IUT − It stands for intra uterine transfer. In this technique, embryos with more than 8 blastomeres are transferred into the uterus.
• GIFT − It stands for gamete intra fallopian transfer. In GIFT, females who cannot produce ovum, but can provide suitable conditions for the fertilisation of ovum, are provided with ovum from a donor.
• ICSI − It stands for intra cytoplasmic sperm injection. In this method, sperm is directly injected into the cytoplasm of the ovum.
• Artificial insemination − In this technique, the semen collected from the husband or a donor is injected into the vagina or uterus. This cures the infertility arising from the inability of the male partner to ejaculate, or due to low sperm count.
• Surrogacy - Surrogacy is another method which is used for women who face problem in implantation of embryo in uterus. In this technique the donor of the oocyte is the women itself who has problem in implanting the embryo in the uterus. The collected oocyte is fertilized with the sperm of her husband in a test tube. The embryo which is obtained after fertilization is implanted in the uterus of another female who is called the surrogate mother.
• Sperm bank - It is a new concept which is similar to blood banks. Sperms are collected from the male donors after a thorough medical checkup and stored for future use. These sperms are used to fertilize the ovum of the women and then this fertilised ovum is implanted in the uterus of the same women.

Answer:

• In sexually reproducing plants, flowers function as the reproductive organs.
• In flowers, male organ is the stamen and female organ is the carpel.
• Flowers which have both the male and female organs i.e. stamens and carpels are called bisexual flowers whereas flowers which have either male or female organs are called unisexual.
• Male gametes called pollen grains are produced by stamen, and carpels produce female gametes called ovules or egg cells inside ovaries.
• Fertilization takes place in the ovule where the egg cell and pollen grain fuse.
• This fertilized egg cell later develops into an embryo and the entire ovule gets converted into a seed.
• Under favourable conditions, the seed germinates to give rise to a new plant.