Reproduction in Lower and Higher Animals

Q. 1 Multiple choice questions.

1. The number of nuclei present in a zygote is ……

a. two b.one c. four d.eight

ANS:  b. one

 A zygote is formed when a sperm cell fertilizes an egg cell, resulting in the fusion of their nuclei. Therefore, a zygote has only one nucleus.

2. Which of these is the male reproductive organ in human?

a. sperm b. seminal fluid c. testes d. ovary

ANS: c. testes

The testes are the male reproductive organs in humans. They produce sperm and the male hormone testosterone.

3. Attachment of embryo to the wall of the uterus is known as……..

a. fertilization b. gestation c. cleavage d. implantation

ANS: d. implantation

 Implantation is the process by which the fertilized egg attaches itself to the wall of the uterus and begins to develop into an embryo.

4. Rupturing of follicles and discharge of ova is known as ..............

a. capacitation b. gestation c. ovulation d. copulation

ANS; c. ovulation

Ovulation is the process in which the follicles in the ovary rupture and release a mature egg cell, which then travels down the fallopian tube towards the uterus.

5. In human female, the fertilized egg gets implanted in uterus ......................

a. After about7 days of fertilization 

b. After about 30 days of fertilization 

c. After about two months of fertilization

d. After about 3 weeks of fertilization

 ANS: d. After about 3 weeks of fertilization

After fertilization, the fertilized egg or zygote undergoes several cell divisions while it moves down the fallopian tube towards the uterus. The process of implantation occurs around 6-10 days after fertilization, when the zygote attaches to the lining of the uterus.

6. Test tube baby technique is called.........

a. In vivo fertilization 

b. In situ fertilization

c. In vitro fertilization

d. Artificial insemination

ANS: c. In vitro fertilization

The test tube baby technique is a type of assisted reproductive technology (ART) that involves the fertilization of an egg by sperm outside the body in a laboratory dish. This process is called in vitro fertilization (IVF).

7. The given figure shows a human sperm. Various parts of it are labelled as A, B, C, and D .Which labelled part represents acrosome ? 

a. B b. C c. D d. A

ANS: (d)A

 The acrosome is a structure located at the tip of the sperm cell's head, which contains enzymes that are necessary for the sperm to penetrate and fertilize an egg. In the given figure, part B represents the acrosome.

8. Presence of beard in boys is a ............

a. primary sex organ 

b. secondary sexual character 

c. secondary sex organ 

d. primary sexual character

ANS:   b. secondary sexual character

Secondary sexual characteristics are physical traits that develop during puberty and distinguish males and females from each other, such as body hair distribution, voice pitch, and breast development. The presence of a beard in boys is a secondary sexual characteristic.

Q. 2 Answer in one sentence.

1. What is the difference between a foetus and an embryo?

ANS: An embryo is the earliest stage of development after fertilization when the zygote divides and forms a ball of cells.

A fetus is a later stage of development when the embryo has undergone significant growth and differentiation.

2. Outline the path of sperm up to the urethra.

ANS: Sperm are produced in the testes.

They travel through the epididymis where they mature and are stored.

They then move through the vas deferens and into the ejaculatory duct.

Finally, they pass through the urethra and are expelled during ejaculation.

3. Which glands contribute fluids to the semen?

ANS: The seminal vesicles, prostate gland, and bulbourethral gland all contribute fluids to the semen.

4. Name the endocrine glands involved in maintaining the sex characteristics of males.

ANS: The testes produce testosterone, which is the primary hormone involved in maintaining male sex characteristics.

The pituitary gland and hypothalamus also play important roles in regulating male hormones.

5. Where does fertilization and implantation occur?

ANS: Fertilization typically occurs in the fallopian tube when sperm meet the egg.

Implantation occurs in the uterus lining, where the fertilized egg (now called a blastocyst) attaches and begins to grow.

6. Enlist the external genital organs in female.

ANS:  The labia majora, labia minora, clitoris, and vaginal opening are the external genital organs in females.

7. Give two differences between blastula and gastrula.

ANS: Blastula is an early stage of development consisting of a ball of cells surrounding a fluid-filled cavity, while the gastrula is a later stage characterized by the formation of three germ layers and the beginning of organ development.

The blastula stage is typically followed by gastrulation, during which the blastula transforms into the gastrula.

8. What is the difference between embryo and zygote?

ANS: A zygote is formed when a sperm and egg fuse to create a single cell.

The embryo is formed after multiple rounds of cell division and differentiation, and is typically the stage that follows the blastula and gastrula stages.

Q. 3 Fill in the blanks:

1. The primary sex organ in human male is ……….

2. The………. is also called the womb.

3. Sperm fertilizes ovum in the ………….. of fallopian tube. 

4. The disc like structure which helps in the transfer of substances to and from the foetus’s body is called…………

5. Gonorrhoea is caused by ……………bacteria.

6. The hormone produced by the testis is ……………….

ANS: The primary sex organ in human male is the testis.

The uterus is also called the womb.

Sperm fertilizes ovum in the ampulla of fallopian tube.

The disc like structure which helps in the transfer of substances to and from the foetus’s body is called placenta.

Gonorrhoea is caused by Neisseria gonorrhoeae bacteria.

The hormone produced by the testis is testosterone.

Q. 4 Short answer questions.

1. Write a note on budding in Hydra.

ANS:

•  Budding is a form of asexual reproduction.
• In Hydra, the bud develops from an outgrowth of the body called the bud stalk.
• The bud grows into a miniature version of the parent and eventually detaches to become independent.
• The new individual formed through budding is genetically identical to the parent.
• Budding is a continuous process in Hydra and can result in the formation of a colony.

2. Explain the different methods of reproduction occuring in sponges.

ANS:

• Sponges can reproduce both sexually and asexually.
• Asexual reproduction occurs through fragmentation, where a piece of the sponge breaks off and grows into a new individual.
• Sponges can also reproduce sexually by producing eggs and sperm that are released into the water and fertilized externally.
• Some sponges can also reproduce hermaphroditically, where an individual has both male and female reproductive organs and can produce both eggs and sperm.

3. Write a note on IVF

ANS:

• IVF is a form of assisted reproductive technology where eggs and sperm are combined in a laboratory dish to create an embryo.
• The embryo is then transferred into the uterus of the mother or a surrogate.
• IVF is commonly used in cases of infertility or genetic disorders.
• It is a complex and expensive procedure with a low success rate, but has helped millions 

4. Comment on any two mechanical contraceptive methods. 

ANS: 

• Condoms are a type of mechanical contraceptive method that prevent pregnancy by creating a physical barrier that prevents sperm from entering the vagina.
• Cervical caps are another type of mechanical contraceptive method that fit over the cervix to block the sperm from entering the uterus.
• These methods are easy to use, affordable, and readily available, but require consistent and correct use to be effective.

5. Write a note on tubectomy

ANS:

• Tubectomy is a surgical procedure where the fallopian tubes in a woman are cut, tied, or sealed to prevent the eggs from reaching the uterus.
• This results in permanent contraception.
• Tubectomy is a safe and effective method of contraception for women who do not want to have any more children, but it is difficult to reverse.

6. Give the name of causal organism of syphilis and write on its symptoms.

ANS:

• The causal organism of syphilis is a bacterium called Treponema pallidum.
• The symptoms of syphilis include painless sores or ulcers, rashes, fever, swollen lymph nodes, and joint pain.
• If left untreated, syphilis can progress to affect the heart, brain, and other organs, and can even be fatal.

7. What is colostrum?

ANS:

• Colostrum is the first milk produced by the mammary glands of female mammals immediately after giving birth.
• It is rich in antibodies and nutrients that provide immunity and nutrition to the newborn.
• Colostrum helps to protect the newborn against infections and other illnesses, and is an important source of nutrition until the milk supply increases.

Q. 5 Answer the following questions.

1. Describe the phases of menstrual cycle and their hormonal control.

ANS:

• Menstrual cycle is divided into 3 phases: follicular phase, ovulatory phase, and luteal phase.
• In the follicular phase, follicle-stimulating hormone (FSH) is released by the pituitary gland to stimulate the growth of follicles in the ovary.
• Follicles produce estrogen, which causes the endometrium to thicken in preparation for a potential pregnancy.
• As estrogen levels increase, luteinizing hormone (LH) is released, triggering ovulation in the ovulatory phase.
• The ruptured follicle forms the corpus luteum, which produces progesterone to maintain the endometrium.
• If fertilization does not occur, the corpus luteum degenerates, causing progesterone levels to decrease and triggering menstruation.

2. Explain the steps of parturition.

ANS: 

• Parturition, or childbirth, involves three stages: dilation, expulsion, and placental.
• In the dilation stage, the cervix dilates and contractions become stronger and closer together, causing the baby to move down the birth canal.
• In the expulsion stage, the baby is born as a result of continued contractions and pushing by the mother.
• In the placental stage, the placenta and remaining membranes are expelled.

3. Explain the histological structure of testis.

ANS: 

• The testis is composed of seminiferous tubules, which are lined with germinal epithelium.
• The germinal epithelium contains spermatogenic cells that give rise to sperm.
• Surrounding the seminiferous tubules are Leydig cells, which produce testosterone.

4. Describe the structure of blastula.

ANS: 

• Blastula is an early stage of embryonic development characterized by a hollow ball of cells called blastomeres.
• The blastomeres are arranged in a single layer around a fluid-filled cavity called the blastocoel.
• The blastula is surrounded by a layer of cells called the trophoblast, which gives rise to the placenta.

5. Explain the histological structure of ovary in human.

ANS: 

The ovary is composed of two main types of tissue: the cortex and the medulla.

The cortex contains follicles, which consist of a developing oocyte surrounded by layers of follicular cells.

The medulla contains blood vessels, nerves, and connective tissue.

6. Describe the various methods of birth control to avoid pregnancy.

ANS: 

• Hormonal methods: include the pill, patch, injection, and vaginal ring, which use synthetic hormones to prevent ovulation.
• Barrier methods: include condoms, diaphragms, and cervical caps, which physically block sperm from reaching the egg.
• Intrauterine devices (IUDs): are small, T-shaped devices inserted into the uterus to prevent fertilization and implantation.
• Sterilization: includes tubal ligation for women and vasectomy for men, which permanently block the fallopian tubes or vas deferens.
• Natural family planning: involves tracking menstrual cycles and abstaining from sex during the fertile period.

7. What are the goals of RCH programme.

ANS: 

• RCH (Reproductive and Child Health) programme aims to improve the health and well-being of women and children by providing access to a range of reproductive and child health services.
• The goals of the RCH programme include reducing maternal and infant mortality rates, improving access to family planning services, and promoting healthy reproductive and sexual practices

8. Which hormones are involved in parturition?

ANS: 

• Hormones involved in parturition: oxytocin, prostaglandins, and cortisol.
• Oxytocin: stimulates uterine contractions.
• Prostaglandins: help soften and thin the cervix.
• Cortisol: promotes the production of surfactant in the fetal lungs to help with breathing after birth.

9. Which as the function of male accessory glands?

ANS: 

• The male accessory glands, including the seminal vesicles, prostate gland, and bulbourethral gland, contribute fluids to the semen during ejaculation.
• The fluids contain various substances that provide nourishment, protection and motility to the sperm, as well as enhance their chances of fertilization.

10. What is capacitation? Give it’s importance

ANS: 

• It involves the removal of cholesterol molecules from the sperm membrane and changes in the protein structure of the acrosome, which is necessary for sperm to penetrate and fertilize the egg.
• Capacitation is important for successful fertilization, as it enables the sperm to navigate through the female reproductive tract and penetrate the egg's protective layers.

Q. 6 Long answer questions.

1. Explain the following parts of male reproductive system along with labelled diagram showing these parts Testis, vasa deferentia, epididymis, seminal vesicle, proastate gland and penis.

ANS:

• Testis: The testis or testicles are a pair of oval-shaped organs located in the scrotum. The testes produce sperm and the male hormone testosterone. Each testis is made up of seminiferous tubules that produce sperm cells, and interstitial cells (Leydig cells) that produce testosterone.
• Vasa deferentia: These are muscular tubes that carry sperm from the testes to the urethra during ejaculation. The vas deferens is about 45 cm long and is coiled up inside the scrotum.
• Epididymis: The epididymis is a long, coiled tube located on the back of each testis. It acts as a storage and maturation site for sperm. Sperm cells produced in the testes travel through the epididymis, where they gain the ability to move and fertilize an egg.

• Seminal vesicle: These are a pair of glandular structures located behind the bladder. They secrete a thick, yellowish fluid that provides nourishment and energy to sperm cells. This fluid makes up the majority of semen (around 60-70%).
• Prostate gland: The prostate gland is a small gland located just below the bladder. It produces a thin, milky fluid that helps to neutralize the acidity of the vagina and provides a medium for sperm to move in.
• Penis: The penis is a male sexual organ that is responsible for delivering sperm to the female reproductive system. It consists of three parts - the root, shaft, and glans. The shaft is made up of spongy tissue that can fill with blood during an erection, while the glans is the enlarged tip of the penis that contains the urethral opening.

2. Describe female reproductive system of human. 

ANS: The female reproductive system consists of the following organs:

• Ovaries: These are a pair of almond-shaped glands located on either side of the uterus. They produce and release eggs (ovulation) and the hormones estrogen and progesterone.
• Fallopian tubes: These are two narrow tubes that extend from the uterus to the ovaries. They provide a pathway for the egg to travel from the ovary to the uterus. Fertilization usually occurs in the fallopian tubes.
• Uterus: The uterus is a muscular organ that is shaped like a pear. It is where a fertilized egg implants and develops into a fetus. The lining of the uterus thickens and sheds during each menstrual cycle.
• Cervix: The cervix is the lower part of the uterus that connects to the vagina. It contains a small opening called the cervical os that allows sperm to enter and menstrual blood to exit.
• Vagina: The vagina is a muscular tube that connects the cervix to the outside of the body. It serves as the birth canal and is the site of sexual intercourse.

3. Describe the process of fertilization.

ANS: Process of fertilization:

• Fertilization is the process in which the sperm and ovum combine to form a zygote, which will develop into an embryo.
• It occurs in the fallopian tube or oviduct of the female reproductive system, where the released ovum gets transported from the ovary.
• The acrosome (head) of the sperm contains enzymes which help in the penetration of the corona radiata (layer of cells surrounding the ovum) and zona pellucida (outermost layer of the ovum).
• Once the sperm penetrates the ovum, the membranes of the sperm and ovum fuse and the contents of the sperm enter the ovum.
• The entry of the sperm triggers the cortical reaction, in which the cortical granules present in the ovum release their contents into the perivitelline space (the space between the zona pellucida and cell membrane).
• This causes a change in the zona pellucida, making it impenetrable to other sperm.
• The haploid nucleus of the sperm fuses with the haploid nucleus of the ovum to form a diploid zygote, which contains the genetic material from both the parents.
• The zygote starts undergoing cell division and moves towards the uterus, where it will implant in the endometrium and continue to develop into an embryo.

4. Explain the process by which zygote divides and redivides to form the morula

ANS: 

• After fertilization, the zygote undergoes a series of cell divisions through mitosis.
• The first division occurs within 24 hours of fertilization, and the zygote divides into two cells, which are called blastomeres.
• These two blastomeres divide again to form four cells, which divide again to form eight cells, and so on.
• As the number of cells increases, the zygote forms a solid ball of cells, called the morula, which is about the same size as the original zygote.
• The morula continues to divide and eventually forms a hollow ball of cells called the blastula, which will eventually implant into the endometrium of the uterus and continue to develop into an embryo.
• The process of cell division and formation of the morula is regulated by various factors, including the genetic material from both parents and the environment within the fallopian tube.

ANS: