RBSE Solutions For Class 12 Biology Chapter 32: Fertilization in Human | Textbook Important Questions & Answers

RBSE Class 12 Biology Chapter 32 – Fertilization in Human. In this chapter, students can learn in detail about fertilization, types of fertilization, phases of fertilization and process of fertilization. It also deals with artificial insemination, steps or different stages involved in fertilization, including the approach of sperms into the ovum, entry of a sperm, cortical reaction, fusion of pronuclei and significance of fertilization.

These important questions help students to perform exceptionally well in their exams. By practising these important questions, students can analyze their preparation, get a thorough knowledge about all important terminologies and perform their best in the examinations.

RBSE Solutions for Class 12 are the best study material for both class assignments and other board examinations. By practising these important questions, students can gain deep knowledge about the topics explained in this chapter and also help them to be well prepared for their upcoming examinations.

RBSE Class 12 Biology Chapter 32 Important Questions

RBSE Biology Chapter 32: MCQ Type Questions

Q.1. Development of unfertilized eggs is called_________.

(a) Transformation

(b) Metamorphosis

(c) Morphogenesis

(d) Parthenogenesis

Sol: (a) Transformation.

Q.2. Sperms move with the help of_________.

(a) Tail

(b) Head

(c) Acrosome

(d) Middle piece

Sol: (a) Tail

Q.3. Gyanogamone is secreted by_________.

(a) Ovum

(b) Ovary

(c) Spermatid

(d) Graafian follicle cells

Sol: (a) Ovum

Q.4. Which of the following are sites of fertilization in females?

(a) Vagina

(b) Uterus

(c) Spermatheca

(d) Fallopian tubes

Sol: (d) Fallopian tubes.

Q.5. The substance which conserves energy during sperm mobility is called _________.

(a) Androgamone I

(b) Androgamone II

(c) Gynogamone I

(d) Gynogamone II

Sol: (a) Androgamone I

Q.6.The enzyme secreted by acrosome of sperm is called________.

(a) Hyaluronidase

(b) Pepsin

(c) Carboxylase

(d) Dehydrogenase

Sol: (a) Hyaluronidase.

Q.7. Which part of the sperm’s head comes in contact with the ovum during fertilization?

(a) Acronis

(b) Anterior lobe

(c) Acrosome

(d) Acromegaly

Sol: (b) Anterior lobe.

Q.8. Fertilization is _________.

(a) The fusion of two gametes

(b) The fusion of male and female pronuclei

(c) The fusion of two gametes of same species

(d) All of the above

Sol: (c) Fusion of two gametes of same species

Q.9. Importance of fertilizin and antifertilizin in fertilization is _________.

(a) To attract gametes to each other

(b) Protection of sperms

(c) Attachment of the sperms on the ovum surface

(d) All of the above

Sol: (c) Attachment of the sperms on the ovum surface.

Q.10. _________stimulates the egg for the complete maturation.

(a) Fertilization

(b) Internal Fertilization

(c) External Fertilization

(d) All of the above.

Sol: (a) Fertilization.

RBSE Biology Chapter 32: Short and Long Answer Type Questions.

Q.1.Where is fertilizin produced in the human body?

Sol: Fertilizin is the chemical substance released by ovum and it is found in an egg, which plays a primary role in fertilization.

Q.2.Who studied the acrosome reactions?

Sol: Ryuzo Yanagimachi was the first embryologist to study the acrosome reaction. It is the process by which a sperm penetrates into the zona pellucida, allowing it to bind to the plasma membrane of an egg.

Q.3. Who gave the concept of fertilizin?

Sol: Fertilizin is a glycoprotein that is found on the membrane of the ovum. This concept was given by F.R. Lillie.

Q.4. What is capacitation?

Sol: When sperms of humans come in contact with the vaginal discharge then this acquires the capability of fertilization. This process is called capacitation.

Q.5. What is Fertilization?

Sol: Fertilization in humans is defined as the fusion of both the male and female gametes that facilitates the development of a new organism.

Q.6. What is Amphimixis?

Sol: The process involves the fusion of male and female pronuclei (karyogamy) and the fusion of cytoplasm of ovum and the sperm (plasmogamy) is called the amphimixis.

Q.7. What is parthenogenesis?

Sol: The process of the development of the ovum without the process of fertilization is called parthenogenesis. It is a natural form of asexual reproduction in which neither the sperms activate the ovum nor there is an amphimixis.

Q.8. What is the purpose of fertilization?

Sol: The main purpose of fertilization is to combine the haploid chromosome sets of two individuals into a single diploid cell known as the zygote, which is the result of activation of the egg.

Q.9.What happens if fertilization does not occur?

Sol: If fertilization does not occur, there will be no zygote formation and egg will degenerate and shed through the uterine lining.

Q.10. What are the different phases of fertilization?

Sol: The different phases of fertilization include-

  • Penetration- The sperm releases acrosomal enzymes to penetrate inside the egg.
  • Activation-The egg membrane depolarizes.
  • The fusion of nuclei and formation of zygote.

Q.11.What are the different types of fertilization?

Sol: There are two different types of fertilization:

Internal fertilization: The fusion of egg and sperm occurs inside the female reproductive tract.

External fertilization: The fusion of male and female gametes occurs outside the body of the organism.

Q.12.What are the advantages of internal fertilization

Sol: The advantages of internal fertilization are:

  • Chances of fusion of gametes are more.
  • The probability of successful fertilization is increased.
  • The mates are selective.
  • The chances of dehydration of gametes decreases.
  • The young one is protected against the predators and the outside environment and hence, chances of survival are increased.

Q.13. What are the stages of fertilization in humans

Sol: The fertilization process in humans takes place in several stages involving both the chemical and physical events. The different stages of fertilization in humans are mentioned below:

Acrosomal Reaction

Cortical Reaction

The entry of a Sperm

Karyogamy

Activation of Eggs

Implantation

Sex Determination

Q.14.What is the significance of fertilization?

Sol: Fertilization is the biological process of fusion of male and female gametes resulting in the formation of a zygote.

The significance of fertilization are:

  • It makes the egg metabolically active.
  • It stimulates the egg for complete maturation.
  • Copulation path determines the axis of the division.
  • It activates ovum for the continuous mitotic division to develop a new organism.
  • Sex chromosomes of the sperms are X or Y by which it also helps in sex determination.
  • It joins the characters of two parents and develops variations. Thus, it also helps in evolution.
  • It makes the number of the chromosomes diploid (46) in zygote by the fusion of the haploid set of male chromosomes.
  • Formation of the fertilization membrane takes place after the entry of sperms by which polyspermy is checked.

Q.15. What is ovum activation?

Sol: The process of ovum activation is called the cortical reaction. This process begins during the process of fertilization by the release of cortical granules from the egg, which prevents polyspermy – the fusion of multiple sperm with one egg.

Immediately after the penetration of a spermatozoon into the egg, the cortical reactions are initiated to prevent further entry of the spermatozoa.

The chemical substances found in the cortical granules are released in between the plasma membrane and vitelline membrane.

These substances fuse with the vitelline membrane to form the fertilization membrane.

Following metabolic activities are initiated in the ovum after the penetration of sperms:

  • Fertilization cones are formed on the egg surface.
  • Fertilization membrane is formed by the vitelline membrane and cortical granules.
  • The permeability of the plasma membrane is increased.
  • The rate of protein synthesis is increased.
  • Mitotic division starts in the fertilized egg.

Q.16. Describe in detail about fertilization in humans.

Sol: Fertilization in humans is defined as the fusion of both the male and female gametes that facilitates the development of a new organism.

Types of fertilization are human.

There are two different types of fertilization: Internal and External fertilization

  • Internal fertilization

The fusion of egg and sperm occurs inside the female reproductive tract. This type of fertilization is found in all oviparous, including birds, platypus and Echidna and viviparous animals include both humans and animals- dog, cat, cow, sheep, tiger, etc.

There are three ways in which internal fertilization produces offsprings:

Oviparity

The fertilized eggs are laid outside. i.e external environment from the mother’s body without any embryonic development. These eggs receive nourishment from its yolk. For eg., fish, amphibians, reptiles and all birds are all oviparous.

Ovoviviparity

The fertilized eggs are retained in the female, and the embryo receives nourishment from the yolk. When they hatch, the young ones are fully developed. This is seen in some bony fish, sharks, lizards, snakes, etc.

Viviparity

In this, the young one develops inside the mother and receives nourishment through the placenta. Most of the mammals, a few reptiles, and cartilaginous fish are viviparous.

  • External fertilization

The fusion of male and female gametes occurs outside the body of the organism. This type of fertilization is carried out in the aquatic medium and is found in all fishes, amphibians and all echinoderms.

Process of fertilization in humans.

Fertilization involves the fusion of the male and the female gamete, which are released from the respective reproductive organs. Sperms or male gametes are released from the male reproductive organ. These sperms enter the female body through the vagina. Then, they travel through the fallopian tubes where they meet the eggs. Hence, the process of fertilization takes place in the fallopian tubes.

During the process of fertilization, the ovum fuses with the haploid nucleus of the sperm to form the zygote. This zygote divides to form an embryo, which in turn develops into a foetus.

Q.17. What is sperm’s capacitation? Draw a neat labelled diagram showing the path of the sperms in the female reproductive system.

Sol: The capability of fertilizing an ovum of its own species is known as sperm’s capacitation.

Here is the neat labelled diagram representing the path of the sperms in the female reproductive system

Path of the sperms in the female reproductive system

Q.18. What are the advantages and disadvantages of external fertilization?

Sol: Fertilization that occurs outside the body of an organism is known as external fertilization. This type of fertilization is seen in all aquatic animals and in some amphibians.

Advantages of External Fertilization

  • It results in increased genetic variations.
  • It produces a larger number of offsprings.
  • The gametes released can drift and therefore it is easy to find mates.

Disadvantages of External Fertilization

  • The gametes or the zygote desiccate.
  • The sperm might not necessarily come in contact with the eggs.
  • A large number of gametes are left unfertilized and wasted.
  • Predators and other environmental hazards reduce the chances of fertilization.

Q.19. What is Ovum? Draw a neat labelled diagram showing the entry of the sperm into the ovum.

Sol: The ovum also called egg cell is the reproductive cell in the female body. Ovum is 20 times bigger than the sperm cells and has a diameter of about 0.1 mm. It is the primary organ of the female reproductive system. Ovum is the single-cell released from the female reproductive organs, which is capable of developing into a new organism

The entry of the sperm into the ovum

The entry of the sperm into the ovumQ.20. What are the differences between the internal and external fertilization?

Sol: Differences between the internal and external fertilization

Internal Fertilization External Fertilization
The fusion of gametes within the body of the female. Union of the gametes in an external environment (Water bodies).
A less number of gametes are released and deposited inside the body of the female. Multiple gametes (both male and female) released into the external environment.
Only male gametes are discharged into the female genital tract. Both female and male gametes are discharged into the external surroundings.
The complete process of fertilization occurs inside the female body The complete process of fertilization occurs outside the body
There are three types of Internal Fertilization
Viviparity
Oviparity
Ovoviviparity
There are no more types of external fertilization
Mammals, Birds, Tracheophytes, Reptiles, Pteridophytes are examples for internal fertilization Algae, Fish, Amphibians are examples for external fertilization

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