Q1: Which of the following is an example of vegetative propagation in plants? (a) Formation of spores in fungi (b) Development of plantlets on Bryophyllum leaves (c) Fertilisation of egg by sperm (d) Budding in yeast
Solution:
Ans: (b) Explanation: Bryophyllum leaves develop tiny plantlets that grow into full plants, which is a form of vegetative propagation involving only one parent plant.
Q2: What is the primary role of meiosis in sexual reproduction? (a) To increase the chromosome number in gametes (b) To produce genetically identical offspring (c) To halve the chromosome number in gametes (d) To form body cells with diploid chromosomes
Solution:
Ans: (c) Explanation: Meiosis reduces the chromosome number from diploid (2n) to haploid (n), ensuring that when gametes fuse during fertilisation, the normal chromosome number is restored.
Q3: Which structure in a flower receives pollen grains during pollination? (a) Anther (b) Stigma (c) Ovary (d) Filament
Solution:
Ans: (b) Explanation: The stigma is the sticky tip of the pistil that receives pollen grains during pollination, allowing fertilisation to proceed through the formation of a pollen tube.
Q4: In humans, which parent determines the biological sex of the baby? (a) The father (b) The mother (c) Both parents equally (d) Neither parent, it is random
Solution:
Ans: (a) Explanation: The father contributes either an X or Y chromosome, while the mother always contributes an X chromosome. The father's contribution thus determines whether the baby is XX (girl) or XY (boy).
Q5: What happens to the uterine lining if the egg is not fertilised? (a) It remains thick for the next cycle (b) It continues to grow further (c) It sheds along with some blood during menstruation (d) It dissolves into the bloodstream
Solution:
Ans: (c) Explanation: When fertilisation does not occur, the thickened uterine lining is no longer needed and sheds through the vagina along with some blood, a process called menstruation.
Fill in the Blanks
Q1: Asexual reproduction produces offspring that are genetically _____ to the parent.
Solution:
Ans: identical
Q2: The fusion of male and female gametes is called _____.
Solution:
Ans: fertilisation
Q3: In humans, gametes are produced by a special type of cell division called _____.
Solution:
Ans: meiosis
Q4: The release of a mature egg from the ovary every month is called _____.
Solution:
Ans: ovulation
Q5: After fertilisation, the ovary of a flower develops into a _____.
Solution:
Ans: fruit
True or False
Q1: Wind-pollinated flowers produce large, sticky pollen grains.
Solution:
Ans: False Explanation: Wind-pollinated flowers produce light and small pollen grains in large quantities to ensure effective dispersal by air currents and capture by feathery stigmas.
Q2: Budding is a form of asexual reproduction observed in yeast and hydra.
Solution:
Ans: True Explanation: Budding occurs when small outgrowths emerge from the parent organism, grow, and eventually detach to form new independent individuals in both yeast and hydra.
Q3: External fertilisation occurs inside the body of the female organism.
Solution:
Ans: False Explanation: External fertilisation occurs outside the body, typically in water, as seen in frogs and most fish where eggs and sperm meet externally.
Q4: Human females carry XX sex chromosomes and males carry XY sex chromosomes.
Solution:
Ans: True Explanation: Females have two X chromosomes (XX) and males have one X and one Y chromosome (XY), which determines biological sex in humans.
Q5: Prenatal sex determination is legally permitted in India.
Solution:
Ans: False Explanation: Prenatal sex determination is strictly prohibited by law in India to prevent sex-selective abortion and maintain a balanced sex ratio in society.
Match the Following
Column A
Column B
1. Testes
A. Transfer of pollen from anther to stigma
2. Pollination
B. Thickened uterine lining sheds with blood
3. Menstruation
C. Produce sperm and reproductive hormones
4. Ovary (in flower)
D. Fusion of male and female gametes
5. Fertilisation
E. Develops into fruit after fertilisation
Solution:
Ans:
1 - C: Testes are male reproductive organs that produce sperm and secrete hormones controlling sperm production and driving puberty changes in males.
2 - A: Pollination is the transfer of pollen grains from the anther to the stigma of a flower, facilitated by wind, water, insects, or birds.
3 - B: Menstruation is the shedding of the inner uterine lining along with some blood through the vagina, typically lasting three to seven days.
4 - E: After fertilisation occurs, the ovary of a flower enlarges and develops into a fruit while ovules become seeds within it.
5 - D: Fertilisation is the fusion of male and female gametes, forming a zygote that later develops into an embryo during reproduction.
Short Answer Questions
Q1: Explain how vegetative propagation is helpful in agriculture.
Solution:
Ans: Vegetative propagation produces genetically identical offspring, allowing farmers to efficiently propagate desirable plant varieties on a large scale. Techniques like cutting, grafting, layering, and tissue culture are used by scientists and horticulturists. These methods ensure high-yield, disease-resistant crops. For example, tissue culture in banana farming provides mass-produced, disease-free plantlets, eliminating virus-infected individuals and ensuring consistent yields.
Q2: Describe the structure and function of sperm in human reproduction.
Solution:
Ans: Sperm are male gametes produced in the testes through meiosis. Each sperm has a head containing genetic material and a long tail enabling it to swim actively toward the egg. Sperm are very small, produced in millions, and carry no stored nutrients. During sexual intercourse, millions of sperm enter the female reproductive system and swim toward the egg in the oviduct for fertilisation.
Q3: What is the importance of meiosis in creating genetic variation?
Solution:
Ans: Meiosis randomly distributes one chromosome from each pair into each gamete, creating unique combinations. In humans with twenty-three chromosome pairs, the possible combinations are enormous. This random mixing ensures children are genetically different from their parents and siblings. Genetic variation is crucial for species survival, helps organisms adapt to changing environments, and drives evolution over many generations.
Q4: Describe the stages of the menstrual cycle in human females.
Solution:
Ans: The menstrual cycle typically lasts twenty-eight days. Days one to five involve menstruation where the uterine lining sheds. Days six to fourteen involve rebuilding the uterine lining and egg maturation. Day fourteen marks ovulation when the ovary releases a mature egg. Days fifteen to twenty-eight involve further thickening of the uterine lining. If fertilisation does not occur, the cycle repeats as the lining breaks down.
Q5: Why do fungi produce millions of spores during reproduction?
Solution:
Ans: Fungi such as Rhizopus and Aspergillus reproduce through spore formation. Spores are lightweight, usually single-celled, and float easily through air currents. A single mould colony can release millions of spores because many are lost during dispersal or fail to find suitable conditions. Large numbers ensure that at least some spores will encounter moisture and nutrients, germinate rapidly, and establish new colonies.
Long Answer Questions
Q1: Analyse the differences between asexual and sexual reproduction in terms of genetic variation and species survival.
Solution:
Ans: Asexual reproduction involves a single parent producing genetically identical offspring through mitosis, allowing rapid population growth under favourable conditions but offering no genetic variation. Sexual reproduction involves two parents contributing genetic material through meiosis, creating genetically varied offspring. This variation helps species adapt to changing environments and drives evolution. While asexual reproduction is efficient, sexual reproduction provides long-term survival advantages by enabling populations to evolve new traits, resist diseases, and adapt to environmental challenges over generations.
Q2: Compare pollination strategies in wind-pollinated and insect-pollinated flowers. Justify why each strategy suits its mode of pollination.
Solution:
Ans: Wind-pollinated flowers like wheat and maize produce light, small pollen in large quantities (five to ten lakh grains per flower) with long, feathery stigmas to trap airborne pollen. Insect-pollinated flowers like sunflower and hibiscus have brightly coloured, fragrant petals producing nectar to attract pollinators. Their pollen is large, sticky, or spiny to cling to insect bodies. Wind pollination relies on chance dispersal, requiring massive pollen production. Insect pollination is more targeted, requiring fewer pollen grains but investing energy in attracting pollinators.
Q3: Evaluate the importance of maternal health during pregnancy and explain how it affects the baby's development.
Solution:
Ans: A pregnant woman's health directly affects the baby's development throughout the nine-month pregnancy. She should eat a balanced diet rich in proteins, vitamins, and minerals to support foetal growth. Regular medical check-ups monitor both mother and baby. Avoiding smoking, alcohol, and unprescribed medicines prevents harm to the developing foetus. Light exercise and adequate rest maintain physical well-being. Emotional well-being is equally important; family support reduces stress. Poor maternal health can lead to complications, premature birth, or developmental issues, making comprehensive care essential.
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