How Do Organisms Reproduce?
Q1: Why simply copying of DNA in a dividing cells not enough to maintain continuity of life?
Answer: Copying of DNA along with creation of an additional cellular apparatus is necessary.
Q2: How does plasmodium undergo fission?
Answer: Plasmodium divides into many daughter cells simultaneously
Q3: How spirogyra reproduces by fragmentation?
Answer: Breaks up into smaller pieces, on maturation each fragment grows into new individual.
Q4: Which cells are responsible for budding in Hydra?
Answer: Regenerative cells
Q5: On which plant can you find buds on its leaves?
Q6: Write the scientific name of the bread mould.
Q7: Name the structure into which following develops : the plumule and radicle?
Answer: plumule -> shoot. radicle -> root.
Q8: Where are the testes located in human beings?
Answer: Outside abdominal cavity in scrotum.
Q9: For what specific reason have the testes specific location?
Answer: sperm formation requires lower temperature 2-3 degrees below than normal body temperature.
Q10: Correlate the rate of general body growth and maturation of reproductive tissue during
Answer: Body growth rate slows down while reproductive tissues (organs) begin to mature.
Q11: Where does the zygote get implanted in human beings?
Answer: In wall of uterus
Q12: Which two important chemical substances are delivered to developing embryo through
Answer: Glucose and oxygen
Q13: Name the tissue in mother's body that provides nutrition to developing embryo?
Q14: How change in hormonal balance prevents pregnancy?
Answer: It prevents the release of eggs.
Q15: Write one side effect of loop placed in uterus?
Answer: Causes irritation and excessive bleeding in uterus.
Q16: Which structures need to be blocked in males and females respectively to prevent pregnancy?
Answer: Vas deferens in male (vasectomy), fallopian tube in female (tubectomy)
Q17: Write the ill effects of misuse of surgery?
Answer: Foeticide (killing girl child).
Q18: Why is children sex ratio alarmingly declining in our country?
Answer: sex selective abortions
Q19: Name the chemical methods of preventing pregnancy.
Answer: Oral pills
Q20: Name some of the devices used as mechanical method for preventing pregnancy.
Answer: loop, copper T, condoms
Q21: Name the only mammal(s) which lays eggs?
Answer: Duck-billed platypus and echidna.
Q22: Define Parthenogenesis.
Answer: Parthenogenesis is a type of asexual reproduction where the embryo development takes places without fertilization. A few species of insects, bees, wasps, birds and lizards (e.g. Komodo Dragon lizard) reproduce this way.
Q23: Name the various types of asexual reproduction
Answer: Various types of asexual reproduction are:
- Spore formation,
- tissue culture
Q25: What is the full form of AIDS?
Answer: Acquired Immune Deficiency Syndrome
Q26: Give examples of organism that reproduce by spore formation.
Answer: Bacteria, Fungi(rhizopus), moss, algae
Q27: Give examples of plants which reproduce by stems.
Answer: Plants like potato (tuber), onion(bulb) reproduce by vegetative propagation of stems.
Q28: What are various artificial vegetative propagation techniques?
Answer: Various artificial vegetative propagation techniques are:
- tissue culture
Answer: A diploid zygote formed by the fusion of male and female gamete is called oospore.
Q30: Give example of plants where self-pollination is observed.
Answer: Pea and China rose
Q31: Give example of plants that do cross-pollination.
Answer: Most of plants do cross-pollination e.g. sunflower, tulip
Q32: What is allogamy?
Answer: Another name of cross-pollination.
Q33: Give examples of surgical methods to birth control.
Answer: Tubectomy (females) and Vasectomy (males)
|Watermelon by Parthenocarpy|
Answer: It is development of fruit without fertilization. Fruits are called virgin-fruits or seedless fruits. Examples are watermelons, grapes etc.
Q35: Give examples of organisms which are Hermaphrodites.
Answer: Earthworm, leech, starfish.
Hermaphrodites are bisexual organisms which possess both male and female reproductive organs.
Q36: Give examples of unisexual animals.
Answer: Birds, Mammals etc.
Q37: What is syngamy?
Answer: The process of fusion of male gamete with female gamete is called syngamy.
Q38(CBSE 2005): Write the full form of IUCD
Answer: IUCD stands for IntraUterine Contraceptive Device - or Copper T - a mechanical barrier method used in females for birth control.
Q39(CBSE 2011): What will happen when Planaria gets cut into two pieces?
Answer: Each part of the Planaria grows into a new organism. It is an example of asexual reproduction by fragmentation.
Q40(CBSE 2011): Out of the following plants which two plants are reproduced by vegetative propagation?
jasmine, wheat, mustard, banana
Answer: jasmine, banana
Q41: Give examples of plants which have unisexual flowers
Answer: papaya, watermelon
Q42: Give examples of plants which have bisexual flowers.
Answer: Hibiscus, mustard
Q43: If a woman is using copper-T will it help in protecting her from sexual transmitted diseases?
Answer: No. copper-T will not protect the women from STDs. It is a barrier method for birth control i.e. kill sperms but do not kill STD causing microbes.
Q44: How does copper-T work?
Answer: Copper-T releases copper ions which mix with uterine fluid. When this ions-rich fluid come in contact with sperms, it kills these sperms and hence avoid pregnancy.
Q45: What are the advantages of Autogamy or Self-pollination?
Answer: Advantages of Self-pollination are:
- It is a sure method of seed formation.
- Scent and Nectar are not needed by the flower to attract insects.
- Parent characteristics are preserved in offsprings.
- Small quantity of pollen is required for pollination.
- Flowers need not be large or attractive.
Q46: What are the disadvantages of Self-pollination?
Answer: Disadvantages are:
- Plants loose their vigor in their future generations due to repeated self-pollination.
- Since there is no variation, no genetic improvement occurs in offsprings.
- Weak characters of the plant are inherited by the next generations.
Q47: What is Allogamy?
Answer: Cross-pollination is known as allogamy. It is the process of transfer of pollen from the anther of a flower to stigma of a flower of another plant of the same species or closely related species.
Q48: Define germination.
Answer: The seed contains the future plant or embryo which develops into a seedling under appropriate conditions. This process is known as germination.
Q49: What is grafting?
Answer: In grafting, one part of a plant is inserted into another plant in a way that both of them will unite and grow together as a single plant.
Q50: What are different types of grafting techniques?
Answer: Different methods of grafting are:
- Approach grafting
- Cleft grafting
- Bud grafting
- Tongue grafting