Extra Questions for Class 10th: Ch 8 How do Organisms to Reproduce? (Science) Important Questions Answer Included
Very Short Answer Questions (VSAQs): 1 Mark
Q1. Name the part of Bryophyllum where the buds are produced for vegetative propagation.
Answer
Leaf notches.
Q2. Name the method by which Hydra reproduces. Is this method sexual or asexual ?
Answer
Hydra reproduces by Budding. It is an asexual reproduction.
Q3. Name the causative agent of the disease "Kala-azar" and its mode of asexual reproduction.
Answer
Leishmania, Binary fission.
Q4. List two functions of ovary of human female reproductive system.
Answer
Two functions of Ovary :
(i) To Produce female gamete / ovum.
(ii) To secrete femele hormones / estrogen and Progesterone
Q5. In the human female reproductive system where does fertilization occur?
Answer
Oviduct or Fallopian tube.
Short Answer Questions-I (SAQs-I): 2 Marks
Q1. What is binary and multiple fission? Name the organisms in which they occur.
Answer
Binary fission is the division of one parent cell into two identical daughter cells. It takes place in Amoeba, Paramecium, Euglena and other protozoa.
Multiple fission is the process in which one single celled organism divides into many daughter cells within a cyst. These are released when the cyst breaks. This takes place in Plasmodium (malarial parasite).
Q2. What is budding? Name two organisms that reproduce asexually by budding.
Answer
In budding a small part of the parents body grows out as a bud which then detaches
and becomes a new organism. Hydra and yeast reproduce by budding.
Q3. What is germination of seed?
Answer
When the seed gets the right conditions the embryo within it starts growing to form the shoot and the root. When the embryo emerges out of the seed to form a new seedling it is called the germination of seed.
Q4. What is menstruation? Why does it occur?
Answer
Menstruation is the process of breakdown and removal of the inner lining of the uterus along with the blood vessels in the form of vaginal bleeding. This happens after every 28 days if the egg is not fertilised. This takes place in human females and in some primates.
Short Answer Questions-II (SAQs-II): 3 Marks
Q1. What are three advantages of vegetative propagation ?
Answer
Three advantages of vegetative propagation:
(i) Plants unable to produce viable seeds can be produced by this method.
(ii) By this method, Plants can bear flowers and fruits earlier than those produced from seeds.
(iii) The characters (traits) of the parent plant can be preserved by this method.
Q2 . What is the effect of DNA copying, which is not perfectly accurate, on the reproduction process ? How does the amount of DNA remain constant though each new generation is a combination of DNA copies of two individuals?
Answer
Reproduction results in the production offspring similar to parents in body design and form. The exact blue prints of body design is inherited in the offspring due to DNA replication. The imperfect DNA copying results in genetic variations. This can be both useful and harmful for the offspring.
The useful variations gets selected in nature and helps organism to survive in the changing environment while as harmful variation gets eliminated.
If each new generation is to be the combination of the DNA copies from two pre-existing individuals, then each new generation will end up having twice the amount of DNA that the previous generation had. In sexual reproduction, the gametes usually contain half number of chromosomes and same numbers present in the body cells. These haploid gametes when fuse produce a new cell with double number of chromosomes than the gametes and same as the body cells. In this way organisms restrict doubling of DNA and maintain the chromosome number.
Q3. (a) With the help of a diagram, show asexual reproduction in Rhizopus ?
(b) How this method is advantageous for Rhizopus ?
(b) How this method is advantageous for Rhizopus ?
Answer
(a) Spore formation takes place in Rhizopus. Rhizopus consists of fine thread like projection called hyphae. It has a knob like structure which is involved in reproduction called sporangia, containing spores, that develop into new Rhizopus.
More number of spores are produced which can easily help Rhizopus to spread.
Q4. In the context of reproduction of species state the main difference between fission and fragmentation. Also give one example of each.
Answer
Fission : It is the method of asexual reproduction in unicellular forms of life. In this process the parent organism splits to form two or more daughter cells. Example : Ameoba
A Fragmentation : It Is the process found in multicellular organisms. The filament breaks up into two or more pieces upon maturation. These pieces then grow into new individuals.
Example : Spirogyra.
Long Answer Questions (LAQs): 5 Marks
Q1.(a) State in brief the functions of the following organs in the human female reproductive system: Ovary, Fallopian tube, Uterus.
(b) Why mensuration take place?
Answer
(a)
• Functions of Ovary:
(i) Production of female gamete
(ii) Production of female hormone
• Functions of Fallopian tube:
(i) Site of fertilization
(ii) Transfer of female gamete from ovary Functions of Uterus:
(i) Implantation of zygote/ fertilise egg/embryo.
(ii) Nourishment to the developing embryo.
(b) Menstruation- It is the periodic breakdown of uterine lining and its removal along with blood and mucous in (post puberatal stage of a) human female. Uterine lining is required to nourish the embryo that is formed if fertilization takes place. In absence of fertilization, the lining is not required and hence is shed in the form of menstruation.
Q2. (a) Write the name of the male reproductive organ that produces sperms and secrete a hormone. Name the hormone secreted and state its function.
(b) Write the site of fertilization and the part where the zygote gets implanted in the human female.
(c) State, in brief, how an embryo gets its nourishment inside the mother's body.
(b) Write the site of fertilization and the part where the zygote gets implanted in the human female.
(c) State, in brief, how an embryo gets its nourishment inside the mother's body.
Answer
(a) A testosterone is the hormone produced in the testes that stimulates the development of secondary sexual characters in males. Its important functions are :
(i) Development, maturation and functioning of the male accessory sex organs like vas deferens and seminal vesicles.
(ii) Stimulate muscular growth, growth of facial hair, low pitch voice, etc., sperm production. All these activities are hindered in the absence of testosterone.
(b) Fertilization takes place in ampulla region of fallopian tube and zygote gets implanted in the uterus.
(c) Embryo is present in the womb of a mother where it is connected with the uterine wall of mother by placenta. The foetus receives oxygen, nourishment and other life supporting things from mother through this placenta.