Class 10 Science Chapter 7 Board Questions

Its filament breaks up into smaller fragments or pieces and each fragment grows into a new filament/individual.

Gonorrhoea, syphilis and AIDS.
Advice to prevent them:
(i) Use of condoms.
(ii) Do not share injection needles/syringe.

Reproduction is a process by which new individuals of the some species are produced by existing organisms(parents).

Asexual and sexual.

DNA on the chromosome.

Banana.

Unicellular organisms, e.g., Amoeba, reproduce by cell division. A parent cell can divide into two or more daughter cells during this. This is called fission. So, cell division is a type of reproduction in unicellular organisms.

Multiple fission.

In my opinion multiple fission is better because at a time many daughter cells will be produced.

(i) Jasmine (ii) Rose

(i) Rose
(ii) Bryophyllum.

(i) Rose
(ii) Sugarcane.

Uterus.

Papaya, watermelon

Grass, Maize.

Stigma.

AIDS, Acquired Immuno Deficiency Syndrome.

Seeds contains the future plant in the form of embryo that develops into seeding in favourable condition.

280 days about 40 weeks (nine months).

The ovary contains embryo sac which has an egg- the female gamete.

Stamen and pistil have germ cell.

Ovary produces egg and fallopian tube carries it to the womb.

(i) Sexual reproduction.
(ii) Asexual reproduction.

Sperm production require little lower temperature compared to body temperature hence testis are located outside.

Sexually transmitted diseases each caused due to bacterial infection and viral infection is gonorrhea. These diseases are curable. Disease caused by viral infection is AIDS. This disease is not curable. These can be prevented by use of condoms during sexual act.

In human female, fertilisation takes place in the fallopian tube After fertilisation, the fertilised ovum travels to uterus and gets attached to the wall of uterus for further development. This is called implantation.

If fertilisation fails to take place the thick and spongy lining of uterus which is formed to receive the fertilisation ovum breaks and comes out through the vagina as blood and mucous. This cycle take place every month and is known as menstrual cycle.

In bryophullum, vegetative propagation occurs through leaves where buds occur while in rose leaves do not form buds. Thus its fallen leaves do not produce new plants.

In bryophullum, vegetative propagation occurs through leaves where buds occur while in rose leaves do not form buds. Thus its fallen leaves do not produce new plants.

This process is called Tissue culture.
Genes possessed by new plant will be same as that of parent plant, resulting in formation of clones.

Organisms produced by asexual reproduction contain exactly the same chromosomes as the parent cell have. Hence they look like clones because the trait remains preserved. Sexual reproduction results in the mixing of gametes of two individuals, hence variation occurs in offspring leading to evolution.

Pollination is landing of pollen grain on suitable stigma. It may not always result in fertilisation. However, fertilisation requires both male and female gametes. If pollination does not occur male gamete is not available. Hence fertilisation cannot taken place.

(i) Appearance of pubic hair.
(ii) Skin become oily and may break into pimples.

Germination: The development of the embryo contained in the seed into seedling under favourable condition is called germination.
Fertilization: The fusion of male germ cell with the female gamete is known as fertilization.

This process is called Tissue culture.
Genes possessed by new plant will be same as that of parent plant, resulting in formation of clones.

Organisms produced by asexual reproduction contain exactly the same chromosomes as the parent cell have. Hence they look like clones because the trait remains preserved. Sexual reproduction results in the mixing of gametes of two individuals, hence variation occurs in offspring leading to evolution.

Pollination is landing of pollen grain on suitable stigma. It may not always result in fertilisation. However, fertilisation requires both male and female gametes. If pollination does not occur male gamete is not available. Hence fertilisation cannot taken place.

(i) Appearance of pubic hair.
(ii) Skin become oily and may break into pimples.

Germination: The development of the embryo contained in the seed into seedling under favourable condition is called germination.
Fertilization: The fusion of male germ cell with the female gamete is known as fertilization.

Reproduction is the process by which an organism produces new individuals that looks very much like themselves.
Importance of DNA copying in reproduction:
(i) Copying or duplication of genetic material through faithful replication is called DNA copying. It can be inherited by the progeny.
(ii) The process of DNA copying brings some variation each time. The surviving cells are similar to but subtly different from each other. This inbuilt tendency for variation during reproduction bring variations among individuals of the same species. This is useful for ensuring survival of the species.

(a) The role of seminal vesicles and prostate gland are as follows:
(i) Seminal vesicles produce seminal plasma with in the form of fluid makes the transport of sperm smooth.
(ii) Prostate gland secretes prostatic fluid take keeps the sperms alive and help them to swim vigorously.
(b) In human being testes perform dual function:
(i) Production of sperm
(ii) Secretion of male hormone testosterone.

Amoeba- Asexual reproduction
Human being – Sexual reproduction
Whale– Sexual reproduction
Hydra– Asexual reproduction
Spirogyra– Asexual reproduction
Dog– Sexual reproduction

(i) Plant grown by vegetative propagation are genetic similar to the parent plant.
(ii) They can bear fruit and flower faster than those plants that are produced by seeds.
(iii) Plants that do not produce seeds too can be multiple by this method.

Pollen on landing on a suitable stigma grows the pollen tube so as to reach the female gamete in the ovary. The pollen tube carries two male gametes in it, which fuse with the egg cell to form zygote and other male gamete fuses with secondary nucleus to form PEN.
After fertilisation the ovary grows rapidly and ripens to form a fruit. After fertilisation the ovule develops a tough coat and it gradually converted into a seed.

Yeast a unicellular fungus reproduces by budding.
When a yeast cell grows to became an adult cell, a small protuberance appears on it. The nucleus splits and the daughter DNA is given into this bud. The bud may detach as an independent yeast cell from parent cell or remain attached on the parent cell as a chain.

(a)
(i) Pregnancy
(ii) Mensturation
(b) In first case the lining of uterus became thick and spongy richly supplied with blood helps in implantation of embryo.
In second case the lining brakes along with blood vessels and come through vagina as menstrual flow.

(a) Vas deference deliver the sperms from the testis to the urethra.
(b) The egg is transferred through fallopian tube from ovary to uterus.

Syphilis, Gonorrhoea, AIDs, wants are sexually transmitted disease.
These infectious diseases spread from one person to other by sexual contact with an infected person.
Fluid discharge, burning sensation while urination, sores in genital area etc., some of the symptoms of STDs.

(a) Seminal vesicles/prostate gland
(b) Testes
(c) Placenta
(d) Fallopian tube

(i) Plants raised by vegetative propagation bear flower and fruits earlier.
(ii) Plants that do not produce seeds can be propagated by this method.
(iii) All plants produced are genetically identical.
(iv) Any vegetative plant part can be used. Thus many new plants can be produced at a time.

(i) Organisms reproduce and create new individuals of their kind. This is essential for perpetuation of species.
(ii) Information the inheritance of features from parent to next generation is present within chromosomes in the form of DNA. The DNA is information source for making proteins, which if changes will change the original body design.
(iii) DNA copying is as essential process toward formation of new cells. This may not always be accurate and thus results in variations. Variations are essential for evolution, but very slow in this case.

Many plants can give rise to new plants through their vegetative parts as roots, stem and leaves. This is known as vegetative propagation.
Following are the advantages (any two):
(i) Plants grown by vegetative propagation are genetically similar to the parent plant.
(ii) Plants that do not produce seeds too can be multiplied by this method.
(iii) Plants raised by vegetative propagation can bear flower and fruits earlier than those produced from seeds.
(iv) Such methods also make possible the propagation of plants such as banana, orange, rose and jasmine that have lost the capacity to produce seeds.
(v) Thus, desirable features of parent plant can be retained and expressed without any change in future generation.
Following are the disadvantages:
(a) All plants are genetically identical to the parent plant and hence no variation.
(b) Because of no variation they would not show any evolution if propagated solely by vegetative propagation.

Different methods of contraception are:
(i) Barrier method- Where physical like condoms (worn over penis), diaphragm (used by female), cervical cap and Copper-T (an IUCD) are used.
(ii) Chemical method- Spermicidal applications by women, vaginal pills or oral contraceptive pills (OCP)s are used. OCPs are hormonal preparations which alter the hormonal level in female body. Use of OCPs is not meant for males.
(iii) Surgical method- Portion of vas deferens in male (vasectomy) or portion of fallopian tube in female (tubectomy) is cut or ligated. This stops releases of gametes, preventing fertilisation.
Contraceptive methods should be adopted as:
(i) They help in spacing two children.
(ii) Thus helps in maintaining a woman’s health.
(iii) Better care of mother and child.
(iv) Also prevention of sexually diseases on using condoms.
(v) This results in better productivity of a family and hence more prosperity.

The transfer of pollen grains from the anther to suitable stigma is termed pollination. Pollination is of two types:
(i) Self-pollination: The transfer of pollen grain from the anther of a flower to the stigma of the same flower is known as self-pollination.
(ii) Cross-pollination: The transfer of pollen grain from the anther of one flower to the stigma of another flower growing on same or another plant of the same species is called cross-pollination.
Agencies of pollination are- wind, water, insects, birds and animals.

In vegetative propagation new plant can be obtained from vegetative parts such as stem, root and leaves. Examples:
(i) Sugar came is grown by using stem cuttings.
(ii) Leaf of Bryophyllum has buds on its margins. When it falls or touches the soil, new plants arise from these buds.
Two advantages of vegetative propagation:
(i) It is the only means of propagating such plants which do not produce visible seeds or produce very few seeds such as banana, orange, grape, rose and pineapple.
(ii) Many identical plants having same characters can be raised from a single parent, by from a single plant, this method.

The organ that produce sperms is Testis. Hormone produced by testis is testosterone. Sperms have to swim to reach the female gamete, which is stationary. Hence they have tails.

Organ where ova are formed is ovary. Ova are released from ovary into the fallopian tube which lead into the uterus. The ovum gets fertilised in the fallopian tube where sperms travel to fertilise the egg from cervix, through uterus, to fallopian tube.
The fertilised egg, i.e., zygote gets implanted in the uterus after fertilisation.

Chromosome are carries of genetic information which is inherited from generation to generation.
Number of chromosomes in sexually reproducing organisms is maintained. This has been achieved by having special lineages of cells in specialised organs which have only half the number of chromosomes and thus half the amount of DNA. Thus, when this germ cells from two individuals combine during sexual reproduction to form a new individual, it results in reestablishment of the number of chromosome and DNA content in the new generation.

Significance of reproductive health in a society:
(i) Reproductive healthy individuals will give rise to healthy new generation.
(ii) There will be fewer sexual transmitted diseases.
(iii) Healthy mothers mean happy households.
(iv) Healthy individuals mean more productive and prosperous families and society at large.
In last 50 years, government has strictly imposed ban on child marriage and hence maternal mortality rate and infant mortality rate has gone down.

Sexual reproductive involves gametes from two different individuals. Thus their genetic make up is different and hence gametes carry different alleles.
It leads to formation of greater variation, so better adaptability and evolution.

(a) Functions of the following in human male reproductive system-
(i) Testis- Production of male hormone i.e., testosterone and male gametes i.e., sperms.
(ii) Vas deferens- Delivers sperms.
(iii) Urethra- Helps in transporting sperm out of the male reproductive tract, is common passage for both sperms and urine.
(iv) Prostate-Adds its secretion to the sperm so that they are in fluid medium which provides them with nutrition and makes the transport easier.
(b) Two changes in males during puberty-
(i) Appearance of facial hair.
(ii) Voice begins to crack.
(iii) Occasional enlargement of penis.
(iv) Muscular body.

Four mode of asexual reproduction are:
(a) Fission- Parent cell divides to form two or more daughter cells.
(b) Fragmentation- Multicellular organisms breaks into pieces and each undergoes cell division to develop into complete organisms.
(c) Regeneration- Multicellular organisms breaks into piece and each undergoes cell division and differentiation (by specialised cells) to form complete organisms.
(d) Budding- A small outgrowth on the parent body detaches when mature and develops into a new individual.

(a) The transfer of pollen from anther to stigma of suitable flower is pollination.
This results in fertilisation and hence formation of next generation.
(b) After pollination, the pollen germinates to form pollen tube that carries male germ cells. It grows to reach embryo sac, where these germ cells are released and fertilisation takes place.
(i) Embryo sac forms seed.
(ii) Ovary forms the fruit.

Along the path of the vas deference these glands add their secretions so that the sperms are now in fluid which make their transport easier and this fluid also provides nutrition to sperms.

Living organisms reproduce mainly by two methods:
(i) Asexual reproduction: In this mode of reproduction, the offspring arises from a single individual parent. Asexual type of reproduction takes place in unicellular organisms, some plants and certain multicellular animals like sponges and Hydra.
Main types of asexual reproduction are:
(a) Fission.
(b) Budding.
(c) Spore formation.
(d) Regeneration.
(e) Vegetative propagation.
(ii) Sexual reproduction: For sexual reproduction, involvement of the two sexes, male and female, is essential. Sexual reproduction involves union of sperm (male gamete) and egg (female gamete). These gametes are produced by gonads testis in males and ovary in females.

(a) Multicellular organisms with cell differentiation, when cut in small pieces, may regrow into complete organisms, e.g. Planaria and Hydra. This process is known as regeneration.
Regeneration is also seen in Hydra
(b) Adventitious buds present on the leaf margin at notches begin to grow to give rise to a new plant, when Bryophyllum leaf falls on wet soil.
(c) In many fungi, like Rhizopus, spore formation takes place in spore sacs called sporangia. These spores, being thick walled, survive harsh conditions and can grow into a complete organism under favourable conditions.
Spore formation is the most common method of asexual reproduction seen in fungi and bacteria. During spore formation, a structure called sporangium develops from the fungal hypha. The nucleus divides several times within the sporangium and each nucleus with a bit of cytoplasm, develops into a spore.
The spore is liberated and they develop into hypha after reaching the ground e.g., Rhizopus, Mucor and Penicillium.

(a) Placenta is a special tissue having disc like shape which remains embedded in the uterine wall. It contains villi on the embryo side of the tissue. On the mother’s side are blood spaces which surrounds the villi. This provides a large surface area for glucose and oxygen to pass from the mother. The developing embryo also generate waste substances which can be removed by transferring them into the mother’s blood through placenta. Apart from it placenta also secretes certain hormones which maintain the pregnancy.
(b) Bacterial diseases transmitted through sexual contact:
(i) Gonorrhoea
(ii) Syphilis
Viral diseases:
(i) Warts
(ii) HIV-AIDS
Use of condoms is the most effective contraception device to prevent STD’s.

(a) (i) Male gametes (sperms) and male hormone testosterone are produced by testis. This
temperature is 1-3 0 C lower than the temperature of the body. Testis are located outside the abdominal cavity, in the scrotum to provide right temperature.
(iii) The sperms formed are delivered through the vas-deferens which unites with a tube coming from the urinary bladder.
(iv) The prostate glands secrete the fluids which provides nutrition to the sperms and make their transport easier.
(b) They require a lower temperature than the human body temperature for the formation of sperms.

(a) Intra Urine Contraceptive Device (IUCD) like Copper-T prevents implantation.
(b) Selective Medical Termination of Pregnancy (MTP) of female foetus using amniocentesis is the main reason behind decline female-male sex ratio in our country. This is because many sections of our society considered girl child as a burden.
Measures to achieve 1:1 ratio.
(i) Generating awareness about girls begin equal helping bands in the family income.
(ii) Banning prenatal sex determination tests.
(iii) Banning certain ill practices in our society like dowry system.
(c) (i) Testis-Anther
(ii) Ovary-Ovary
(iii) Egg-Female gamete/egg
(iv) Sperms-Male gamete in pollen tube.

For implantation of foetus, a special tissue called placentae develops from the maternal uterine wall. It is a disc shaped structure, in the uterine wall with villi on the embryonal side and large blood spaces on maternal side.
Functions:
(i) It provides large surface area for glucose O2 to pass from mother’s blood to the embryo.
(ii) It also removes embryonal metabolic wastes.

(a) Variation is occurrence of differences between organisms.
Variation are created in a population in different ways:
(i) There may be minor changes/errors during DNA copying mechanisms which happens before any cell division. These variations may go on accumulating from previous generations, ultimately leading to visible changes.
(ii) In sexually reproducing organisms, the traits of two individuals combine and give rise to new combination in the progency. This also leads to variation.
(iii) Thus combining variations from two or more individuals would thus create new combination of variations.
Organisms with suitable variations will have better chances of survival. Depending on the nature of variations, different individual would have different kind of advantages.
(b) In sexually reproducing organisms each cell has two copies of each chromosomes one each from the male and female parent. During gamete formation one chromosomes from each pair goes to a gamete. Hence the gametes have half the number of chromosomes but one chromosomes of each pair. When two gametes combine they restore the normal number of chromosomes in the progeny.

Pollination is the process of transfer of pollen grains from anther to stigma of the same flower or of different flower of same species.
It occurs with the help of various biotic and abiotic agencies. For example,
Biotic- Birds, insects and bats help in pollination.
Abiotic- Air and water also help in pollination.
Step lading from pollination to fertilisation.
(i) Pollen grain lands on suitable stigma, grows out pollen tube carrying the two male gametes.
(ii) First male gametes fuse with the egg cell resulting in formation of the diploid zygote. The zygote develops to form embryo which later forms complete plant.
(iii) The second male gamete fuses with the two polar nuclei to form triploid PEN. Primary endosperm nucleus to develop zygote.