Zoology: Solved Previous Year Question Paper for NCERT/ CBSE Class 12th Zoology Paper code (SEIIRKO-13-81020-Q) 

Zoology: Solved Previous Year Question Paper for NCERT/ CBSE Class 12th Zoology Paper code (SEIIRKO-13-81020-Q)

(Long Answer type questions) 

Question: Explain the structure of the Human Male Reproductive System’. Illustrate your answer with the help of a neat and labelled diagram

Answer: The male reproductive system consists of both external and internal organs. The external organs are the penis, the scrotum and the testes, while the internal organs include the prostate gland, seminal vesicles, vas deferens and the urethra.

The diagram below illustrates the structure of the human male reproductive system: (Diagram)

1. Penis – The penis is an external organ which is responsible for delivering sperm into the female reproductive tract during sexual intercourse.

2. Scrotum – The scrotum is an external pouch which houses the testes and helps to regulate their temperature.

3. Testes – The testes are two oval-shaped glands which produce sperm and testosterone.

4. Prostate Gland – The prostate gland is an internal organ which produces seminal fluid to nourish and transport sperm.

5. Seminal Vesicles – The seminal vesicles are two internal glands which produce a fluid that helps to nourish and propel sperm.

6. Vas Deferens – The vas deferens is a long, coiled tube which carries sperm from the testes to the urethra.

7. Urethra – The urethra is a long tube which carries sperm and urine out of the body.

Question: Define Fertilization. Briefly enlist the events that take place during Fertilization. 

Answer: Fertilization is the fusion of a sperm cell and an egg cell to form a single cell that has genetic material from both the egg and the sperm.

Events that take place during Fertilization:

1. Sperm binds to the egg and penetrates its outer layer.

2. The sperm and egg nuclei fuse, forming a single nucleus.

3. The egg is activated and begins the process of cell division.

4. The zygote begins to divide into two cells, then four cells, and so on.

5. The zygote starts to travel down the fallopian tube towards the uterus.

6. Once the zygote has reached the uterus, it implants itself in the uterine wall.

7. The placenta and umbilical cord begin to form.

Question: Name the Chromosomal disorders in humans. Explain any two of them in detail. 

Answer: Chromosomal disorders in humans include Down syndrome, Turner syndrome, Klinefelter syndrome, Cri-du-Chat syndrome, and Fragile X syndrome.

1. Down Syndrome: Down Syndrome is a genetic disorder caused by the presence of an extra copy of chromosome 21. It is the most common chromosomal disorder, occurring in approximately 1 out of every 700 live births.

Some common characteristics of Down Syndrome are physical growth delays, low muscle tone, flat facial features, and an upward slant to the eyes. Additionally, intellectual disabilities and developmental delays are common.

2. Turner Syndrome: Turner Syndrome is a genetic disorder caused by a missing or incomplete X chromosome in females. It affects approximately 1 in 2,500 female births. Common features of Turner Syndrome include short stature, a webbed neck, a low hairline at the back of the head, and heart defects. Additionally, there can be various reproductive issues, such as infertility, as well as an increased risk of certain conditions like hearing loss, diabetes, and kidney problems.

Question: Define Hardy Weinberg’s principle. What is its significance?

Answer: Hardy Weinberg’s principle is a population genetics principle stating that the allele frequencies in a population remain constant from one generation to the next in the absence of other evolutionary influences, such as genetic drift, natural selection, and non-random mating.

It is significant because it allows population geneticists to predict the frequencies of alleles and genotypes in a population without the need to observe the population over several generations.

Question: Add a note on adaptive radiation. 

Answer: Adaptive radiation is the process by which a species diversifies and evolves into several different forms as it adapts to different environments. This process is driven by natural selection and can often lead to the formation of new species. It is an important process for maintaining biodiversity and helping species adapt to changing environments.

 (Short Answer Type Questions) 

Question: What is “Placenta”? Write down its main functions.

Answer: The placenta is an organ that develops in the uterus during pregnancy and provides oxygen, nutrients, and hormones to the growing fetus.

Its main functions are to:

1. Provide oxygen and nutrients to the fetus.

2. Produce the hormones necessary for the development and maintenance of the pregnancy.

3. Filter waste products from the fetus and return them to the mother.

4. Produce hormones that prevent the mother’s immune system from attacking the fetus.

5. Regulate the temperature of the fetus.

6. Assist in the delivery of the baby at the end of the pregnancy.

Question: Write a short note on “Ramapithecus”. 

Answer: Ramapithecus is an extinct genus of primates that lived between 10 million and 14 million years ago. It is considered to be one of the earliest known hominids and is believed to be a direct ancestor of modern humans. Its remains were first discovered in India in the 1930s, and more were found in East Africa in the 1950s. Its discovery has helped scientists better understand the evolution of human ancestors.

Question: Write down the causes of “Filariasis”. 

Answer: The main cause of filariasis is infection with parasitic roundworms of the Wuchereria bancrofti, Brugia malayi, and B. timori species. These worms are transmitted to humans through the bite of an infected mosquito.

Question: What is Cloning? What is its significance? 

Answer: Cloning is the process of creating a genetically identical copy of an organism.

Cloning has become a significant tool in the fields of biotechnology and genetic engineering, allowing for the production of identical copies of plants and animals with desirable traits. This has enabled the rapid production of large numbers of genetically identical animals for research purposes, as well as to produce valuable medicines, crop varieties, and other products. Additionally, it has also been used to create genetically modified organisms (GMOs) with improved characteristics.

(Very Short Answer Type Questions) 

Question: Write two major functions of the Testes and Ovary. 

Answer: Testes:

1. Produce and secrete male sex hormones (testosterone) which are responsible for the development of male reproductive organs and male secondary sexual characteristics.

2. Produce sperm, the male gamete (sex cell) necessary for fertilization.


1. Produce and secrete female sex hormones (estrogen and progesterone) which are responsible for the development of female reproductive organs and female secondary sexual characteristics.

2. Produce ova, the female gamete (sex cell) necessary for fertilization.

Question: List down the differences between Homologous and Analogous organs. 

Answer: Homologous Organs:

1. Homologous organs are structurally similar but may have different functions.

2. Homologous organs are found in different species that share a common ancestor.

3. Examples of homologous organs include the wings of a bird and the forelimbs of a bat.

Analogous Organs:

1. Analogous organs are structurally different but may have similar functions.

2. Analogous organs are found in different species that do not share a common ancestor.

3. Examples of analogous organs include the wings of a bird and the fins of a fish.

Question: Write down the symptoms of ‘Typhoid’. 

Answer: Symptoms of Typhoid include: – High fever – Weakness – Headache – Abdominal pain – Loss of appetite – Constipation or Diarrhea – Enlarged spleen and liver – Rose-colored spots on the chest – Sore throat – Cough – Chills – Confusion – Fatigue

Question: What do you mean by Recombinant DNA Technology?

Answer: Recombinant DNA technology is a technique used to combine DNA molecules from different sources into a single molecule. It is used to create new combinations of genetic material that could not be found in nature.

 (MCQ/Objective Type Questions) 

Question: (i) Expand the terms MTP and STD. 

Answer: MTP means (medical termination of pregnancy)

STD means Sexually transmitted diseases (STDs)

Question:  (ii) Monozygotic twins are——- of their parents and ———- each other. (Fill up) 

Answer: genetically identical, share the same genetic information

Question:  (iii) “Peripatus” is a connecting link between Annelida and Mollusca, whether true/false 

Answer: True

Question: (iv) Write down the scientific name of the Silkworm.

Answer: The scientific name of the Silkworm is Bombyx mori.

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