Class 10 Science Chapter 7 MCQ

Here, all the statements are correct. Hence, your answer will be option [D].

Sperms formed in testis are delivered through the vas deferens which joins with another tube called urethra, coming from the urinary bladder.

Development of placenta and secretion of estrogen are related to female reproductive system. Hence, are not the function of testis at puberty.

Formation of germ cell or sperms take place in the testes and it lies in the scrotum. In the scrotum outside the abdominal cavity, the temperature is about 3 degree Celsius lower than the temperature of the body. Testes lies in the scrotum because the sperm formation require a lower temperature than the normal body temperature.

Spores are the microscopic a sexual reproductive body which are covered by a hard-protective coat. This coat enables them to survive under unfavorable condition like lack of food, lack of water and extreme temperatures. But when the conditions are favorable, then the spores grow to produce new plants. Thus, spores are a kind of seeds of plants.

In early e teenage girls should, breast size increased with darkening of the skin of nipples at the tip of breast. Also, girls begin to menstruate at around this time. In human females, this reflects onset of reproductive phase.

Cracking of voice is associated with second maturation is boys which occurs during adolescence. During teenage a new set of changes occurs in boys and girls. In boys, there are changes includes growth of hair on face, cracking of voice etc. Loss of milk teeth, increase in height and weight gain are the normal process of growth in both boys and girls as the body grows older.

It is “not” necessary to plant the whole potato tuber in the ground to produce the new potato plants. We can even plant, to “cut pieces” of a potato tuber in the ground to obtain new plants potato plants. But all these cut pieces of potato tuber should have a bud or eye on them. Each potato plant produces more than one tuber and each tuber has more than one bud which produce more than one new plant. Due to this, the vegetative propagation method of producing potato plants by tuber is much faster than the production of potato plants from seeds.

The new plants produced by artificial vegetative propagation will be exactly like the parent plants. Any desirable features of the parent plant will be replicated in the new plants.

Sexual reproduction creates variation in organisms. So, clones cannot be produced through it. Clones are identical copy of parent organism. Sexual reproduction needs two types of “Gametes” i.e. male and female to form zygote after fertilization.

The flowers are unisexual (papaya, watermelon) contains either stamens or carpels. Since only one reproductive organ is present in them. They depend on cross pollination to form zygote after fertilization. Both stamen and carpels are required for fertilization, so only one of them cannot produce fruits.

The replication or copying of DNA in the cells is done by certain biochemical reaction which synthesize more of genetic material. When the DNA already present in the nucleus of the parent cell is replicated or copied by making more DNA at the time of “asexual reproduction”, then slight variation come in the two copies formed. Due to this, the two DNA molecules formed by replication will be similar but may not be exactly identical to the original DNA. No biochemical reaction can produce 100% same results.

In sexual reproduction, though the genetic material DNA from two gametes, male and female gametes, combined together to form a new cell “zygote” but the amount of DNA in zygote does not get the doubled. This can be explained as: When a male gamete combined with the female gamete during sexual reproduction, then the new cell zygote will have the normal amount of DNA or normal number of chromosomes in it. For example, the human sperm has 23 chromosomes and the human egg or ovum has also 23 chromosomes. So, when a sperm and an egg fuse together during fertilization, then the zygote formed will have 23 + 23 = 46 chromosomes, which is the normal number of chromosomes.

Here, all the statements are correct. Hence, your answer will be option [D].

Length of pollen tube depends on the distance between pollen grain on upper surface of stigma and ovule. A pollen grain falls on the stigma of the carpel, bursts, open and develops a pollen tube downwards through the style towards the ovule in the ovary.

Here, all the statements are correct. Hence, your answer will be option [D].

The first occurrence of menstruation at puberty is called menarche. And the permanent stoppage of menstruation in a woman is called menopause. Menopause occurs in women at the age of about 45 to 50 years.

In vegetative propagation, vegetative parts of a plant such as root, stem leaf, etc. can produce new plants. Vegetative reproduction is seen in plants like orchids, ornamental plants, grasses, banana, rose, jasmine etc.

The thread like structure of the bread mould, Rhizopus are called hyphae. The tiny blobs present on them which contains cells or spores are sporangia. The spores eventually develop into new Rhizopus individuals, when they come in the contachment an other-most surface.

The number of chromosomes in parents and off-springs of a particular species remains constant due to halving of chromosome during gamete formation. The gametes are a special type of cells which contain only half of the amount of DNA as compared to normal cells of an organism. So when a male gamete combines with a female gamete during sexual reproduction, then the new cell “zygote” will have normal amount of DNA.

In Spirogyra, asexual reproduction take place by fragmentation, i.e. organisms simply breaks up into smaller pieces upon maturation. Each pieces is grow into new individuals without forming any gametes.

In sexual reproduction, the offspring are not identical to the parents or to one another. This is because the offspring receives some genes from mother and some genes from father. Because of mixing of genes on re-establishment of number of chromosome in various different combinations, the off spring show both similarities and variations with characters of parents.

Characters are transmitted from parents to offspring through genes. Genes are the hereditary units of the body in living organisms. Chromosomes in the nucleus of a cell contain information for the inheritance of features from parents in the form of DNA (Deoxyribonucleic acid). This DNA contains genes.

Offspring have greater similarity as only one parent is involved in a sexual reproduction thus no garments one former. The basis of asexual reproduction is mitosis (division of a nucleus into two identical daughter nuclei). Each daughter nucleus has same genetic makeup because of replication of parental DNA. The new offspring produced are called clones.

In a flower, the parts that produce male and female gametes are anther and ovary respectively. Stamen is the male reproductive unit of the flower. It contains a bilobed anther at the top which produces male gametes. Filament is the stalk of the stamen that supports anther. Pistil (carpel) is the female reproductive part of the flower. It consists of ovary (forms ovules-female gametes), stigma (receives pollen) and style (elongated tube).