Science [5 marks Questions]

a) Sperm formation will be adversely affected because it requires a lower temperature than the body temperature.
b) Vas deferens is a passage for transfer of sperms, so sperms will not be transferred further.
c) When prostate and seminal vesicles are not functional, they will not add secretions for nourishment and medium for the transport of sperms.
d) When an egg is not fertilised in a human female, it lives for about one day. Then, the thickened lining of the uterus breaks leading to discharge of blood and mucus along with the unfertilised egg. This is called menstruation.
e) Nutrition and oxygen will not be provided to the growing embryo affecting its growth, which could have serious implications as well.

1.  

Parts where:

1. Eggs develop–Ovary.
2. Fertilisation take place–Fallopian tubes.
3. Fertilised egg gets implanted–Uterus.

2.  

1. The inner uterus lining (endometrium) becomes thick and soft with lots of blood capillaries before of a fertilised egg (zygote). The uterus has to keep this zygote for further development and supply it with food, oxygen, etc.
2. If the egg is not fertilised, then the uterus lining break down along with its bloods vessels in the form of vaginal bleeding called menstrual flow.

1.  

A– Pollen grains.

B– Pollen tube.

C– Ovary.

2. The transfer of pollen grains from anther (male sexual part) of a flower to the stigma part of the pistil (female sexual part) is known as pollination.

Signification of pollination: It may be the cause of variation in a species of a plant.

3. Fertilisation in flower: A pollen grain contains two male gametes. When a pollen grain falls on the stigma of the carpel, it grows a pollen tube downwards into the style. One of the male gametes reaches the ovary through pollen tube and fuses with female gamete present in the ovule. This fertilisation of the two germ cells style. One of the germ cells forms a zygote. The zygote is capable into new plant.

The other male gamete fuses with two polar nuclei to form endosperm nucleus. This fusion is called triple fusion. The zygote grows into an embryo and an endosperm nucleus grows into endosperm. (the food storage tissue of seed)

1. All the eggs in the ovule present in the ovary of a flower gets fertilised by male gametes from the pollen grains and grow to become seeds.
2. The ovary of flower develops and becomes fruit.

1.  

1. Ovary: They produce eggs or the female gamete. They also produce the female hormone estrogen which brings about the development of secondary sexual characters in females.
2. Oviduct: Carries the mature egg to the uterus. The oviduct provides the place for fertilization to occur.
3. Uterus: It nurturing the fertilized ovum that develops into the fetus and holding and supporting it till the baby is mature enough for birth.

2. Placenta is a disc which is embedded in the uterine wall. It contains villi on the embryo’s side of the tissue. On the mother’s side are blood spaces, which surround the villi.

The placenta provides a large surface area for glucose and oxygen to pass from the mother to the embryo. The waste substances generated by the foetus are removed by transferring them into the mother’s blood through the placenta.

1. Testes produce sperms and secrete a hormone called testosterone. The function of testosterone is to control the development of male sex organs and male features such as a deeper voice, moustache, beard and more body hair as compared to females.
2.  

1. Fertilisation takes place in the oviduct or fallopian tubes.
2. Implantation of the fertilised egg occurs in the uterus.

After implantation, a disc-like special tissue called placenta develops between the uterus wall and the embryo. The placenta helps in the exchange of nutrients, oxygen and waste products between the embryo and the mother. Thus, it provides nourishment to the growing embryo.

The transfer of pollen grains from anthers (male sexual parts) of a flower to the stigma part of the pistil (female sexual part) is known as pollination. Pollination is done by insects, birds, wind and water. Pollination can occur in two ways:

1. Self-pollination: When the pollen grains from the anther of a flower are transferred to the stigma of the same flower or another flower on the same plant, it is called self-pollination.
2. Cross pollination: When the pollen grains from the anther of a flower on one plant are transferred to the stigma of a flower on another similar plan it is called cross-pollination.

When a pollen grain falls on the stigma of the carpel, it grows a pollen tube downwards through the style towards the female gamete in the ovary. A male gamete moves down the tube. When the pollen tube enters the ovule, its tip bursts open and male gamete comes out of the pollen tube and combings with the nucleus of the female gamete and forms zygote. This process is known as fertilisation.

The two causes of population explosion are:

1. Decline in death rate (including maternal mortality rate and infant mortality rate).
2. Increase in the number of people in the reproducible age.

Following are the ways to check population explosion:

1. One-child norm.
2. Increasing the marriageable age.
3. Promoting contraceptive methods.

Contraceptive methods are of two types:

1. Natural means of contraception.
2. Artificial means of contraception.

Natural Methods:

1. Avoiding the coming together of ovum and sperm.
2. Periodic abstinence: Avoiding coitus from days 10 to 17 of the menstrual cycle.
3. Coitus interrupts: Withdrawal of penis before ejaculation.
4. Lactational amenorrhea: It is the absence of menstruation during lactation. So, in the lactation period, the chances of conception are almost zero.

Artificial Methods:

1. Physically preventing the coming together of ovum and sperm.
2. Barriers: Include condoms, diaphragms, cervical caps and vaults.
3. Intra uterine devices (IUDs): They release hormones to cause phagocytosis of sperms, or they release copper ions to decrease sperm motility.
4. Oral contraceptive pills: They contain hormones-either progesterone or progesterone-oestrogen combination.
5. Surgical methods: Include vasectomy (removal of a part of the vas deferens in males) and tubectomy (removal of a part of the fallopian tubes in females).

In the female reproductive system, the part that:

1. Produces egg: Ovary.
2. Fusion of egg and sperm takes place: Fallopian tube.
3. Zygote is implanted: Uterus.

Diagram of female reproductive system:
The ovary releases one egg every month. The uterus also prepares itself every month to receive a fertilised egg. The inner uterus lining (endometrium) becomes thick and is supplied with blood to nourish the embryo. If the egg is not fertilised, then the uterus lining is not required. Hence, it breaks down and is released in the form of blood and mucus through the vagina. This process lasts for 2-8 days and is known as menstruation.

Unisexual Flowers	Bisexual Flowers
The flower has either male reproductive organs (stamens) or the female reproductive organs (pistil)	The flower has both the male reproductive organs (stamens) and the female reproductive organs (pistil) in a single flower.
Example: Papaya.	Example: Hibiscus.

Diagram showing germination of pollen grain on stigma:

Binary fission which means division in half. It is a kind of asexual reproduction. It is the most common form of reproduction in prokaryotes and occurs in some single-celled eukaryotes. After replicating its genetic material, the cell divides into two nearly equal sized daughter cells.
In unicellular organisms like Amoeba cell division, or fission, leads to the creation of new individuals. The parent cell simply splits into two equal halves during cell division. In organisms such as Amoeba, the splitting of the two cells during division can take place in any plane.
It takes place in the following steps:

1. Parent cell enlarges and the nucleus develops constriction.
2. The cytoplasm divided with the two nucleuses.
3. The cell divides into two.

The hydra reproduces by the process of budding by the use of regenerative cells. It carries out the process in the following steps:

1. A bud develops as an outgrowth due to repeated cell division at one specific site.
2. The buds develop into tiny individuals.
3. When fully mature, these buds detach from the parent body and become new independent individuals.

1.  

1. Part that produces pollen grain: anther
2. Part that transfers male gamete to the female gamete: style
3. Sticky part to trap pollen grain: stigma
4. Part that develops into fruit: Ovary

2.  

Pollination	Fertilization
Pollination is the process of transfer of pollen grains from anther to the sligma of the same or different flower.	Fertilization is the process of fusion of male gamete with the female gamete.
It takes place with the help of pollinations like wind, water insects etc.	It takes place by the growth of pollen tube toward the ovary.

1. Placenta is a temporary organ which is formed from the tissues derived from the foetus and the mother. The placenta contains villi on the embryo’s side of tissue and blood spaces on the mother side of tissue. The blood space surrounds the villi. The villi provides a large surface area for glucose and oxygen to pass from the mother to the embryo. Thus, through placenta, the maternal blood passes food (glucose, amino acids, lipids and proteins), oxygen, hormones, water, antibodies to the foetal blood and the foetal metabolic wastes (carbon dioxide, urea) pass into the maternal blood.
2. BACTERIAL INFECTION: This includes gonorrhoea (inflammation of mucus membrane of urinogenital tract) and syphilis (lesions in the mucus membrane of urinogential tract)

VIRAL INFECTION: This includes warts, HIV-AIDS, Hepatitis-B.
Use of condoms can prevent the spread of these diseases to a great extent.

1.  

Functions of Ovaries:

1. The ovaries produce eggs (also called ova) and female hormones(These hormones control the development of female body characteristics, such as the breasts, body shape, and body hair).
2. The ovaries also regulate the menstrual cycle and pregnancy.

Functions of Fallopian tubes:

1. The fallopian tubes connect the ovaries to the uterus. One egg cell each month is released from the ovaries floats down the fallopian tubes, and into the uterus.

Functions of Uterus:

1. Uterus is the place where a foetus develops.
2. The uterus provides structural integrity and support to the bladder, bowel, pelvic bones and organs.
3. The reproductive function of the uterus is to accept a fertilized ovum which passes through the utero-tubal junction from the fallopian tube.

2. Menstruation (men-STRAY-shuhn) is a woman's monthly bleeding. When you menstruate, your body sheds the lining of the uterus (womb). Menstrual blood flows from the uterus through the small opening in the cervix and passes out of the body through the vagina. Most menstrual periods last from 3 to 5 days.

Unisexual Flower: Papaya/Watermelon.
Bisexual Flower: Hibiscus/Rose.
Self-pollination: The pollen grains are transferred from the anther to the stigma of the same flower or to the flower of the same plant.
Cross pollination: The pollen grains are transferred from the anther to the stigma of a flower of a different plant.

• After pollen lands on a suitable stigma, a pollen tube grows out of pollen grain and travels through the style to reach the ovary.
• The male germ cell fuses with the female germ cell to form a zygote.
• Zygote divides several times to form an embryo within the ovule.
• The ovule develops tough coat and gradually gets converted into a seed.

Definition: It is the production of plants from vegetative parts of the plant like stem, root, leaf etc. In vegetative propagation, a portion is detached from the body of the parent plant and is grown independently.
Advantages of vegetative propagation:

1. For propagation of plants that produce little or no viable seeds.
2. Many fruits are cross pollinated, so to provide consistent quality without variation vegetative propagation is preferred.
3. Most often easier, rapid and more economical method.
4. Flowering period is short compared to seed propagated plants.
5. Method of choice in propagating plants in unfavorable environmental condition.

Jasmine and banana are grown by this process.

1. Testis is the male reproductive organ in humans that produces sperms and also secretes the testosterone hormone. Important functions of testosterone are as follows:

Stimulates the development, maturation and functioning of the male accessory sex organs like vas deferens and seminal vesicles Stimulates muscular growth, growth of facial hair, low pitch voice, sperm production, etc.

2.  

1. Fertilisation takes place in the fallopian tube (oviduct).
2. Implantation of the fertilised egg occurs in the uterus. The embryo develops inside the mother’s body for about nine months.

3. Inside the uterus, the outer tissue surrounding the embryo develops finger-like projections called villi. These villi are surrounded by uterine tissue and maternal blood. They provide a large surface area for the exchange of oxygen and nutrients. There is a special tissue called placenta embedded in the uterine wall. The embryo receives the oxygen and nutrients from the mother’s blood via the placenta. The waste material produced by the embryo is removed through the placenta.

1.  

1. Ovaries are primary reproductive organs in a woman. Functions:

1. To make mature female sex cells called 'ova' or eggs.
2. To produce the female sex hormones called estrogen and progesterone.

2. Oviduct also known as fallopian tubes. Functions:

1. To transfer the female gametes (egg) from ovary to uterus.
2. The fertilization of egg (or ovum) by a sperm takes place in the oviduct.

3. Uterus: two oviducts are connected to bag like organ called uterus (womb) Functions:

1. The growth and development of a fertilized ovum into a baby takes place in the uterus.

2. The embryo gets nourishment inside the mother's body through placenta that is a disc like special tissue that develops between the uterus wall and the embryo. It is through the placenta that all the other requirements of the developing foetus also like respiration, excretion etc., are met from mother's body.

1. Part of human female reproductive system:

1. Ovary produces egg in females.
2. Fusion of eggs and sperm takes place in the fallopian tube.
3. Zygote gets implanted in the uterus of the female reproductive system.

The diagram below shows Female reproductive system.

2. The zygote formed after fertilization in the fallopian tube is implanted in the uterus. It divides repeatedly to form a mass of cells known as embryo. This embryo gets attached to the inner layer of the uterine cavity, i.e., endometrium. It thickens every month and is supplied with blood to nourish the embryo. Soon it gets covered by rapidly dividing uterine cells. This leads to pregnancy. Within a span of some months, the embryo starts developing limbs and begins to resemble a miniature being. When all parts of the embryo can be recognized, it becomes a foetus. The mother gives birth to the baby when the foetus fully develops.

1.  

Unisexual Flower – Papaya.

Bisexual Flower – Hibiscus.

2. After fertilisation, the fertilised egg divides several times to from an embryo within the ovule. The ovule develops a tough coat around it and is gradually converted into a seed (containing the baby plant along with food).The ovary of flower develops and becomes a fruit (with seeds inside it). The other parts of flower like sepals, petals, stamens, stigma and style dry up and fall off. Only the ovary is left behind.
3. In sexual reproduction, though the genetic material DNA from two gametes, male and female gametes, combine together to from a new cell ‘zygote’ but the amount of DNA in zygote does not get doubled. This is because the gametes are special type of cells which contain only half the amount of DNA as compared to the normal body cells of an organism. So the new cell zygote formed by tow gametes cells will have the normal amount of DNA.

1. Testis is the male reproductive organ in humans that produces sperms and also secretes the testosterone hormone.

Important functions of testosterone are as follows:

Stimulates the development, maturation and functioning of the male accessory sex organs like vas deferens and seminal vesicles Stimulates muscular growth, growth of facial hair, low pitch voice, sperm production, etc.

2.  

1. Fertilization takes place in the fallopian tube (oviduct).
2. Implantation of the fertilized egg occurs in the uterus.

3. The embryo develops inside the mother's body for about nine months. Inside the uterus, the outer tissue surrounding the embryo develops finger-like projections called villi. These villi are surrounded by uterine tissue and maternal blood. They provide a large surface area for the exchange of oxygen and nutrients. There is a special tissue called placenta embedded in the uterine wall. The embryo receives the oxygen and nutrients from the mother’s blood via the placenta. The waste material produced by the embryo is removed through the placenta.

1.  

1. Ovaries are primary reproductive organs in a woman. Functions:

1. To make mature female sex cells called 'ova' or eggs.
2. To produce the female sex hormones called estrogen and progesterone.

2. Oviduct also known as fallopian tubes. Functions:

1. To transfer the female gametes (egg) from ovary to uterus.
2. The fertilization of egg (or ovum) by a sperm takes place in the oviduct.

3. Uterus - two oviducts are connected to bag like organ called uterus (womb) Functions:

1. The growth and development of a fertilized ovum into a baby takes place in the uterus.

2. Placenta is a disc like special tissue that develops between the uterus wall and the embryo. It is through the placenta that all the requirements of the developing foetus like nutrition, respiration, excretion etc., are met from mother's body. It can be said that the exchange of nutrients, oxygen, waste products between the embryo and the mother takes place through the placenta.

1.  

Sr. no	Sexual Reproduction	Asexual Reproduction
1.	It involves both the parent.	It involves only a single parent.
2.	It involves fusion of male and female gametes.	It does not involves fusion of gametes The gametes of single parent undergoes divison and gives rise to new a individual.
3.	It results in the introduction of variation in a population as newly formed organisms are not the exact copies of the parent.	It does not bring variation in a population as the newly formed organisms are identical to the parents.

2. In case of sexual reproduction, there is marked variation between the parent and offspring due to the following reasons:

1. The male and female gametes are formed by meiotic division which allows crossing over and recombination. This generates variation in the genes of offspring.
2. Two parents are involved who are different from each other. The fusion of their gamete would produce a distinct individual.

1.  

A – Stigma, Function – The stigma is a sticky surface where the pollen lands and later germinates.

B – Pollen tube, Function – It carries the pollen to the egg cell for fertilisation.

C – Egg cell, Function – It fuses with the male gamete and leads to the formation of zygote.

2. Role of gametes – The gametes play an important role in the sexually reproducing organisms as they carry the entire genetic information of the organism. These gametes upon fusion result in the formation of zygote, which develops into a new individual. Any deformation in the gametes will lead to the deformity in the newly formed offspring.

Role of zygote – Zygote is the diploid cell formed by the fusion of male and female gametes during fertilisation in sexual reproduction. Zygote is the first stage in the development process of an organism and it contains all the genetic information of both the parents, essential for the growth of the new organism.

Pollination: It is a type of asexual reproduction in which the pollen grains are transferred from the anther of a stamen to stigma of a carpel. Pollination is of two types:

1. Self-pollination
2. Cross pollination

Fertilization: it is a mode of sexual reproduction in which the male gamete is fused with the female gamete to form zygote. This process occurs in both plants and animals. There are two types of fertilization which are as follows:

1. External fertilization.
2. Internal fertilization.

The diagram of a pistil showing pollen tube growth into the ovule is as follows:

1. Testes: The testes are the male reproductive organs that are located outside the abdominal cavity within a pouch called scrotum. It produces sperms and also produces a hormone called testosterone, which brings about secondary sexual characters in boys.
2. Seminal vesicles: The seminal vesicles secretion makes the transport of the sperm easier and the fluid also provides nutrition.
3. Vas deferens: It carries sperm from the vasa efferentia to the urethra.
4. Ureter: When blood is filtered by the kidney, the waste material (urine) is passed on to urinary bladder via the ureters. The function of ureter is to carry urine from the kidney to the urinary bladder.
5. Prostate glands: It produces an alkaline fluid (prostatic fluid), which is a constituent of the semen. The prostatic fluid provides motility, longer survival period (neutralizes the acidic environment of the female reproductive tract) and protection to sperms.

1. The diagram of the longitudinal section of a flower is as follows:

2. Stamen is the male reproductive part of a flower. Carpel is the female reproductive part of flower.

1. Fragmentation: It is a mode of asexual reproduction when a organisms simply break down into several parts or fragments in order to reproduce a new individual.

Ex: Spirogyra

2. Regeneration: The process by which some organism replace or restore lost or amputated body parts that have been cut/ damaged by external factors. It is also a mode of asexual reproduction as these organisms regrowth its parts separately sometimes when they have been removed into 2 or more.

Ex: Planaria

1. Functions:

1. Ovary:

• Produces ova or female gametes.
• Secretes the female hormones oestrogen and progesterone which are responsible for changes in the female body at the time of puberty.

2. Oviduct:

• Acts as the site for the fertilisation of male and female gametes.
• After fertilisation, the ovum travels down to the uterus through the oviduct.

3. Uterus:

• Protects and nourishes the developing embryo with the help of placenta.

2. Structure and function of placenta:

• Placenta is embedded in the uterine wall and serves as a connecting link between the mother’s body and the baby.
• It is a disc of specialised tissue which provides food and oxygen to the foetus.
• It contains blood spaces on the mother’s side and small projections called villi on the foetal side. Here, the mother’s blood and foetal blood come in contact with each other.
• It provides a large surface area for the exchange of nutrients and oxygen between the mother and the foetus.
• The foetus gives away waste products and carbon dioxide to the mother’s blood for excretion.
• It also functions as an endocrine gland and secretes the hormones necessary to maintain pregnancy.

1. The labelled parts of the female reproductive system are as follows:

1. Oviduct or Fallopian Tube
2. Ovary
3. Uterus
4. Cervix
5. Vagina

2. Contraception includes methods or ways to prevent fertilisation and pregnancy in a fertile female as a result of successful copulation between a fertile male and female.

Some of the major advantages of adopting various contraceptive methods include:

1. Prevention of unwanted pregnancies.
2. Help in family planning and population control.
3. Some contraceptive devices like condoms and female diaphragm prevent spread of STDs like AIDS and Hepatitis B.

Transfer of pollen grain from the anther of a flower to stigma is termed as pollination.
Based on the transfer of pollen grains between plants, pollination can be of two types:

1. Self Pollination: When pollen of a plant is transferred to the stigma of a flower on the same parent plant then it is termed as self-pollination.
2. Cross Pollination: When pollen of a plant is transferred to the stigma of a flower of a plant different from the one from which pollen is obtained then it is termed as cross-pollination.

Some of the most common agents of pollination that helps in carrying the pollen from the anther to the stigma of a flower are insects and wind.
As the pollen of the right type is deposited on to the stigma of the flower of the same species, quite often it leads to germination of pollen grain as a result of a chemical cross-talk between the pollen and the carpel. Germination leads to the growth and extension of the pollen tube through the style of the flower to its ovary. The pollen tube carries the male gametes all the way to the ovule inside the ovary, leading to fertilisation of male gamete with the female gamete inside the ovule,

The testes are composed of coiled structures called seminiferous tubules, which are the sites of sperm production. The structure on top of the seminiferous tubules in the testes is the epididymis. The sperm migrate from of the seminiferous tubules to the epididymis. Within the epididymis, the sperm mature while they are stored in this structure.
The ejaculation process begins as the penis fills with blood and becomes erect. With sufficient stimulation, mature sperm travel from the epididymis through the vas deferens, a muscular tube, which propels sperm forward through smooth muscle contractions. The sperm arrive first at the ampulla, where secretions from the seminal vesicle are added.
From the ampulla, seminal fluid is propelled forward through the ejaculatory ducts toward the urethra, passing first by the prostate gland, where a milky fluid is added to form semen. Finally, the semen is ejaculated through the far end of the urethra.

1. Vasectomy: In males, a small portion of the sperm duct (Vasdeferens) is removed by surgical operation and both the cut ends are ligated properly. This prevents the sperms from coming out.
2. Tubectomy: In females, a small portion of the oviducts is removed by surgical operation and the cut ends are ligated. This prevents the ovum from entering into the oviducts.

1. The device X is condom.
2. Y represents sperms.
3. The device Z is copper-T.
4. The general name of these methods of birth control is called barrier method or IUCD (Intrauterine Contraceptive Device).
5. Using condoms (X) during sexual intercourse can protect a person from sexually transmitted disease.

1. Represents pollen grains. The process of transferring pollen grains from one flower to another flower of the similar plant by insects is known as cross pollination.
2. B represents the pollen tube.
3. C is the male gamete which moves down through the pollen tube (B).
4. D is the female gamete (or egg). The structure E represents the ovule.
5. F is the zygote.

1. A represents the vas deferens.
2. B represents sperms.
3. C represents the testes.
4. The cell D is the egg or ova.
5. The surgical method of birth control available to males is called vasectomy.

1. The worm X is Planaria.
2. The organism Y which posses the same characteristic as of X is Hydra.
3. The process in which a complete organism is formed from a lost body part of its parent is regeneration.
4. X and Y are multicellular organisms.
5. A dog cannot be produced from a lost body part like its tail, as this animal has a high degree of organisation in its body.

Followed by fertilization, placenta is developed which serve to provide nutrition and oxygen to developing embryo from the mother's blood. It is a disc embedded in the uterine wall and contains villi on the embryo's side of the tissue while blood spaces surrounding the villi are present on mother’s side. The embryo is connected to the placenta by umbilical cord, a tube like structure.Placenta serves to fulfill all nutritional requirements of developing embryo by supplying food and oxygen from mother’s blood to the embryo. Waste products of developing embryo are removed by transferring them into the mother's blood through the placenta. Functions of placenta are facilitated by villi that provide large surface areas for passage of nutrition and oxygen to embryo from mother through blood.

1. A is gonorrhoea and C is syphilis.
2. B is AIDS.
3. The virus D is Human Immunodeficiency Virus (HIV).
4. A, B and C can be caused by sexual contact with an infected person.
5. AIDS (B) does not have a definite cure as yet.

Two bacterial, sexually transmitted diseases are gonorrhoea and syphilis:

1. Gonorrhoea: It is caused by Neisseria gonorrhoeae. Symptoms, if produced include burning with passage of urine, discharge from penis or vagina, pain in the pelvic region. The disease can be prevented by the use of condoms during sex or having sex with only one, uninfected partner.
2. Syphilis: It is caused by Treponema pallidum species. Symptoms include the presence of a firm skin ulcer, without pain or itching. This disease can be prevented by use of condoms.

1. The alga X is likely to be Spirogyra.
2. The alga is green in colour.
3. This mode of forming new alga from the breaking-up of the parent alga is termed as fragmentation.
4. The splitting of Amoeba is termed as fission, which occurs only in unicellular organisms. The splitting of alga is termed as fragmentation, which occurs only in multicellular organisms.
5. Sea anemone reproduces in the same way as the alga X.

Methods to avoid undesired pregnancy are called contraceptive methods. It includes:

1. Mechanical barrier that prevent arrival of sperm to the egg, e.g., condom.
2. Chemical Drugs or contraceptive pills-Small dosage of female hormones that prevent released of egg.
3. Loop or copper-T-physical devices to prevent pregnancy.
4. Surgical method-permanent contraception by vasectomy and tubectomy.

Surgical methods: Vasectomy refers to surgical method in which vasa deferentia in human males are cut and sealed to prevent pregnancy by making seminal fluid devoid of sperms. Tubectomy refers to surgical process in which oviducts in human females are cut and sealed to prevent pregnancy by inhibiting released of egg.

1. The organism X is yeast and organism Y is Hydra.
2. The process by which the organism X converts sugar into alcohol is fermentation.
3. Organism X is a fungus; hence, it belongs to the category of non-green plants.
4. Organism Y is a multicellular organism and comprises tentacles at one end.
5. Organism X is unicellular, and the organism Y is multicellular.

1. The fertilised egg cell E is also called the zygote.
2. The tissue T is the placenta.
3. The string-like structure S is the umbilical cord.
4. Oxygen and nutrients pass from the mother's blood to the embryo and carbon dioxide passes from the embryo to the mother's blood through the placenta (T).
5. When a baby is born, the umbilical cord is still attached to the baby. It is cut and tied to separate the baby from the mother.

• A is the ovum.
• B is sperm.
• C is the zygote.
• D is the uterus.
• E is the embryo.
• F is the foetus.

The person X is a female and Y is a male.
 

1. The shapeless lump of mass X is known as callus.
2. This method of producing new plants is known as tissue culture.
3. The jelly is called agar.
4. The chemicals used to stimulate the growth of plant cells and fasten the development of roots and shoots are called plant hormones.
5. Orchids and dahlia are two flowering plants that are propagated by this method.
6. The main advantage of this technique is that it is extremely fast, and the plantlets are obtained in a few weeks. Secondly, this method produces disease-free plantlets.
7. The other name of this technique is micropropagation.

DNA copies generated during reproduction will be similar but may not be identical to the original. This statement is correct because copying of DNA also accompanies the creation of an additional cellular apparatus. When the DNA copies are separated from each other, each copy have its own cellular apparatus and from one cell, there is production of two cells due to which copying of DNA brings variation every time. Survival cells are similar to each other but also they have variations from each other too.