10th Science - Book Back Answers - Biology Unit 17 - English Medium Guides

 

SSLC / 10th - Science - Book Back Answers - Biology Unit 17 - English Medium

Tamil Nadu Board 10th Standard  Science - Biology Unit 17: Book Back Answers and Solutions

    This post covers the book back answers and solutions for Unit 17 – Biology from the Tamil Nadu State Board 10th Standard  Science textbook. These detailed answers have been carefully prepared by our expert teachers at KalviTips.com.

    We have explained each answer in a simple, easy-to-understand format, highlighting important points step by step under the relevant subtopics. Students are advised to read and memorize these subtopics thoroughly. Once you understand the main concepts, you’ll be able to connect other related points with real-life examples and confidently present them in your tests and exams.

    By going through this material, you’ll gain a strong understanding of Biology Unit 17 along with the corresponding book back questions and answers (PDF format).

Question Types Covered:

• 1 Mark Questions: Choose the correct answer, Fill in the blanks, Identify the correct statement, Match the following 
• 2 Mark Questions: Answer briefly 
• 3, 4, and 5 Mark Questions: Answer in detail

All answers are presented in a clear and student-friendly manner, focusing on key points to help you score full marks.

All the best, Class 10 students! Prepare well and aim for top scores. Thank you!

Topic: Reproduction in Plants and Animals

I. Choose the correct Answer

1. The plant which propagates with the help of its leaves is:
(a) Onion
(b) Neem
(c) Ginger
(d) Bryophyllum
Answer Key:
(d) Bryophyllum

2. Asexual reproduction takes place through budding in ______.
(a) Amoeba
(b) Yeast
(c) Plasmodium
(d) Bacteria.
Answer Key:
(b) Yeast
 
3. Syngamy results in the formation of:
(a) Zoospores
(b) Conidia
(c) Zygote
(d) Chlamydospores
Answer Key:
(c) Zygote

4. The essential parts of a  flower are ______.
(a) Calyx and Corolla
(b) Calyx and Androecium
(c) Corolla and Gynoecium
(d) Androecium and Gynoecium.
Answer Key:
(d) Androecium and Gynoecium.

5. Anemophilous flowers have:
(a) Sessile stigma
(b) Small smooth stigma
(c) Colored flower
(d) Large feathery stigma
Answer Key:
(d) Large feathery stigma

6.Male gametes in angiosperms are formed by the division of ______.
(a) Generative cell
(b) Vegetative cell
(c) Microspore mother cell
(d) Microspore.
Answer Key:
(a) Generative cell

7.What is true of gametes?
(a) They are diploid
(b) They give rise to gonads
(c) They produce hormones
(d) They are formed from gonads
Answer Key:
(d) They are formed from gonads

8. A single highly coiled tube where sperms are stored, get concentrated and mature is known as ______.
(a) Epididymis
(b) Vasa efferentia
(c) Vas deferens
(d) Seminiferous tubules.
Answer Key:
(d) Seminiferous tubules.
 
9. The large elongated cells that provide nutrition to developing sperms are:
(a) Primary germ cells
(b) Sertoli cells
(c) Leydig cells
(d) Spermatogonia
Answer Key:
(b) Sertoli cells

10. Estrogen is secreted by ______.
(a) Anterior pituitary
(b) Primary follicle
(c) Graafian follicle
(d) Corpus luteum.
Answer Key:
(b) Primary follicle
 
Question 11.
Which one of the following is an IUCD?
(a) Copper – T
(b) Oral pills
(c) Diaphragm
(d) Tubectomy
Answer Key:
(a) Copper – T

II. Fill in the blanks

1. The embryo sac in a typical dicot at the time of fertilization is ………
2. After fertilization the ovary develops into ………
3. Pianaria reproduces asexuallv by ………
4. Fertilization is ……….. in humans.
5. The implantation of the embryo occurs at about ……….. day of fertilization.
6. ………. is the first secretion from the mammary gland after child birth.
7. Prolactin is a hormone produced by …………
Answer Key:
1. Double fertilization
2. Fruits
3. Regeneration
4. Internal
5. 6 to 7
6. Colostrum
7. Anterior pituitary

 

III. Match the folloing

1. Match the following

Column I		Column II
1	Fission	i	Spirogyra
2	Budding	ii	Amoeba
3	Fragmentation	iii	Yeast

Answer Key:

Column I		Column II
1	Fission	ii	Amoeba
2	Budding	iii	Yeast
3	Fragmentation	i	Spirogyra

 

 

2. Match the following terms with their respective meanings

Column I		Column II
1	Parturition	i	Duration between pregnancy and birth
2	Gestation	ii	Attachment of zygote to endometrium
3	Ovulation	iii	Delivery of baby from uterus
4	Implantation	iv	Release of egg from Graafian follicle

Answer Key:

Column I		Column II
1	Parturition	iii	Delivery of baby from uterus
2	Gestation	i	Duration between pregnancy and birth
3	Ovulation	iv	Release of egg from Graafian follicle
4	Implantation	ii	Attachment of zygote to endometrium

IV.  State whether  the following statements are True or False. Correct the false statement.

1. Stalk of the ovule is called pedicle.
2. Seeds are the product of asexual reproduction.
3. Yeast reproduces asexually by means of multiple fission.
4. The part of the pistil which serves as a receptive structure for the pollen is called as style.
5. Insect pollinated  flowers are characterized by dry and smooth pollen.
6. Sex organs produce gametes which are diploid.
7. LH is secreted by the posterior pituitary.
8. Menstrual cycle ceases during pregnancy.
9. Surgical methods of contraception prevent gamete formation.
10. The increased level of oestrogen and progesterone is responsible for menstruation.
Answer Key:
1. False – Stalk of the ovule is called Funiculus
2. False – Seeds are the product of sexual reproduction
3. False – Budding reproduces asexually by means of multiple fission.
4. False – The part of the pistil which serves as a receptive structure or the pollen is called as stigma.
5. False – Wind pollinated flowers are characterized by dry and smooth pollen.
6. False – Sex organs produce gametes which are haploid
7. False – Anterior pituitary (LH is secreted by the Anterior pituitary)
8. True
9. True
10. True

 

V.  Answer in a word or sentence

1. If one pollen grain produces two male gametes, how many pollen grains are needed to fertilize 10 ovules?
Answer Key:
Atleast 10 pollen grains required to fertilise 10 ovules because only one male gamete is involved in the fusion of male gamete with the egg cell.
 
2. In which part of the  flower germination of pollen grains takes place?
Answer Key:
Pollen grains reach the stigma and begin to germinate.
 
3. Name two organisms which reproduces through budding.
Answer Key:
Yeast and hydra reproduce through budding.
 
4. Mention the function of the endosperm.
Answer Key:
The endosperm provides food to the developing embryo.
 
5. Name the hormone responsible for the vigorous contractions of the uterine muscles.
Answer Key:
Oxytocin from the posterior pituitary stimulates the uterine contraction.
 
6. What is the enzyme present in the acrosome of sperm?
Answer Key:
Hyaluronidase is the enzyme, present in the acrosome of sperm, which helps the sperm to enter the ovum during fertilization.
 
7. When is World Menstrual Hygiene Day observed?
Answer Key:
Every year May 28th is observed as Menstrual Hygiene day to make girls and women aware of maintaining menstrual hygiene and importance of menstrual hygiene for good health.
 
8. What is the need for contraception?
Answer Key:
Contraception is used to prevent pregnancy, to check population growth.
 
9. Name the part of the human female reproductive system where the following occurs, (a) Fertilization (b) Implantation
Answer Key:
(a) Fertilization: Occurs in the oviduct of the female genital tract. It takes place usually in the ampulla of the fallopian tube.
(b) Implantation: Blastocyst reaches the uterus (uterine wall) (endometrium)

VI. Short answer questions

1. What will happen if you cut planaria into small fragments?
Answer Key:
Each fragment will develop into a new individual by a specialized mass of cell. It is called regeneration. It is the ability of the lost body parts of an individual organism to give rise to a whole new organism.
 
2. Why is vegetative propagation practised for growing some type of plants?
Answer Key:
The vegetative part of plant, root, stem, leaf or budgets detached from the parent body and grows into an independent daughter plant by mitotic division. The daughter plants are genetically similar to the parent plant.
 
3. How does binary fission differ from multiple fission?
Answer Key:

Binary fission	Multiple fission
Binary fission is the splitting of a cell into two daughter cell.	Multiple fission is splitting of a parent cell into two or more daughter cells.
Takes place in favourable conditions.	Takes place in unfavourable conditions.
Cyst formation is absent.	Cyst formation occurs.
E.g: Amoeba, Paramecium	E.g: Plasmodium

 
4. Define triple fusion.
Answer Key:
The fusion involving two polar nuclei and a sperm nucleus, that occurs in double fertilization in a seed plant and results in the formation of endosperm, is called the triple fusion.
 
5. Write the characteristics of insect-pollinated flowers.
Answer Key:
1. The flowers are brightly coloured to attract insects which have smell and nectar.
2. The pollen grains are larger in size, the exine is pitted, spiny, so they can be adhered firmly on the stucky stigma.
 
6. Name the secondary sex organs in male.
Answer Key:
The secondary sex organs in the male are vas deferens, Epididymis, seminal vesicle, prostate gland and penis.
 
7. What is colostrum? How is milk production hormonally regulated?
Answer Key:
The milk produced from the breast during the first 2 to 3 days after child birth is called colostrum. Milk production from alveoli of mammary glands is stimulated by prolactin secreted from the anterior pituitary.

8. How can menstrual hygiene be maintained during menstrual days?
Answer Key:
Maintaining menstrual hygiene is important for the overall health of women.
• Sanitary pads should be changed regularly, to avoid infections due to microbes from vagina and sweat from genitals.
• Use of warm water to clean genitals, to get rid of menstrual cramps.
• Wearing loose clothing, to ensure the airflow around the genitals, to prevent sweating.
 
9. How does developing embryo gets its nourishment inside the mother’s body?
Answer Key:
The developing embryo gets nutrition from the mother’s blood with the help of a special tissue called placenta. It is embedded in the uterine wall. This is a disc like tissue which develops between the uterine walls and embryo. It has villi of embryo side of the tissue. On the mother side are blood spaces with the villi. This gives a large surface area for oxygen and glucose to pass from the mother to the embryo.
 
10. Identify the parts A, B, C and D.

 

Answer Key:
A – Exine
B – Intine
C – Generative nucleus
D – Vegetative nucleus
 
11. Write the events involved in the sexual reproduction of a  flowering plant.
1. Discuss the first event and write the types.
2. Mention the advantages and disadvantages of that event.
Answer Key:
1. The transfer of pollen grains from the anther to the stigma of a flower is called pollination. Self – Pollination and Cross-Pollination are the two types of Pollination.
2. Advantages:

• It results in fertilization, which leads to the formation of fruits and seeds.
• New varieties of plants are formed, through a new combination of genes,

3. Disadvantages:

• More wastage of pollen grains.
• Pollination may fail due to the distance barrier.
• Flowers depend on external agencies for pollination.

 
12. Why are the human testes located outside the abdominal cavity? Name the pouch in which they are present.
Answer Key:
Human testes responsible for synthesis of male gametes(sperms) need slightly lower temperature than the normal body temperature for this function. Thus, they are located outside the abdominal cavity in a sac like structure called scrotum.
 
13. The luteal phase of the menstrual cycle is also called the secretory phase. Give reason.
Answer Key:
During the Luteal phase of the menstrual cycle in the uterus, the hormone progesterone is produced by the ovaries. Progesterone and estrogen are secreted by the Corpus Luteum, which develops from the Graafian follicle. So this phase of the menstrual cycle is called the secretory phase.
 
14. Why are family planning methods not adopted by all the people of our country?
Answer Key:
Family planning is a way of living that is adopted voluntary by couples on the basis of knowledge and responsible decision to promote the health and welfare of the family group and society. As it is voluntary many people are not aware of the importance of family planning.

VII. Long answer questions

1. With a neat labelled diagram describe the parts of a typical angiospermic ovule.
Answer Key:
Structure of the Ovule : The main part of the ovule is the nucellus which is enclosed by two integuments leaving an opening called as micropyle. The ovule is attached to the ovary wall by a stalk known as funiculus. Chalaza is the basal part.

The embryo sac contains seven cells and the eighth nuclei located within thenucellus. Three cells at the micropylar end form the egg apparatus and the three cells at the chalaza end are the antipodal cells. The remaining two nuclei are called polar nuclei found in the centre. In the egg apparatus one is the egg cell (female gamete) and the remaining two cells are the synergids.

2. What are the phases of menstrual cycle? Indicate the changes in the ovary and uterus.

Answer Key:

Phase	Days	Changes in Ovary	Changes in Uterus
Menstrual phase	4–5 days	Development of primary follicles	Breakdown of uterine endometrial lining leads to bleeding
Follicular phase	6th–13th day	Primary follicles grow to become a fully mature Graafian follicle	Endometrium regenerates through proliferation
Ovulatory phase	14th day	The Graafian follicle ruptures, and releases the ovum(egg)	Increase in endometrial thickness
Luteal phase	15th– 28th day	Emptied Graafian follicle develops into corpus luteum	Endometrium is prepared for implantation if fertilization of egg takes place, if fertilization does not occur corpus luteum degenerates, uterine wall ruptures, bleeding starts

 

 

VIII. HOTS questions

1. In angiosperms, the pollen germinates to produce a pollen tube that carries two gametes. What is the purpose of carrying two gametes when single gamete can fertilize the egg?
Answer Key:
One sperm fuses with the egg (syngamy) and forms a diploid zygote. The other sperm fuses with the secondary nucleus (Triple fusion) to form the primary endosperm. After triple fusion, the primary endosperm nucleus develops into an endosperm. The purpose of carrying two gametes is, endosperm provides food to the developing embryo.
 
2. Why menstrual cycle does not take place before puberty and during pregnancy?
Answer Key:
Menstruation occur when the egg is not fertilized. Every month uterus prepares itself to receive the fertilized egg to nourish the embryo, its lining becomes thick and spongy for implantation of the fertilized egg.
In case egg is not fertilized thin lining breaks and discharged out of the body through the vagina in the form of blood.
This condition will not happen before puberty and during pregnancy.
 
3. Read the following passage and Answer Key the s that follow:
Rohini and her parents were watching a television programme. An advertisement flashed on the screen which was promoting the use of sanitary napkins. Rohini’s parents suddenly changed the channel, but she objected to her parents and explained the need and importance of such advertisement.
(a) What is first menstruation called? When does it occur?
(b) List out the napkin hygiene measures taken during menstruation?
(c) Do you think that Rohini’s objection towards her parents was correct? If so, Why?
Answer Key:
(a) The first period or menstruation is a point in time, known as Menarche. It usually begins between 12 to 15 years of age.
(b)
1. The sanitary pad and tampons should be wrapped properly and discarded because they can spread infections.
2. Sanitary pad or tampon should not be flushed down the toilet.
3. Napkin incinerators are to be used properly for disposal of used Napkins.
(c) No, it was not correct. The parents and teachers have to create awareness among the school girls about the use of Napkins and their proper disposal. Girls should be educated and should know the importance of such advertisement on Television.