Hello, my brilliant students!
Welcome back! You've expertly navigated the 1-mark and 2-mark questions, and I'm so proud of the foundation you've built. Now, it's time to dive deeper.
This post is all about the Short Answer (SA) questions, each worth 3 marks. These questions are the heart of the exam paper and require you to explain concepts with clear, structured points. This is where you really get to show what you know! Let's get started.
Top 30 Short Answer Questions (3 Marks)
Q1. Draw a neat diagram of the longitudinal section of a flower and label its four main whorls.
Answer:
Here is a labeled diagram of a flower showing its four main whorls:
Calyx (made of sepals - the outermost whorl)
Corolla (made of petals - for attracting pollinators)
Androecium (made of stamens - the male part)
Gynoecium (made of the pistil/carpel - the female part)
Q2. Explain the process of budding in Hydra with the help of a diagram.
Answer:
Budding in Hydra is a form of asexual reproduction.
Due to repeated cell division at a specific site, a small outgrowth called a bud develops on the parent's body.
This bud gradually grows and develops a mouth and tentacles, resembling the parent Hydra.
Once fully mature, the bud detaches from the parent's body and becomes a new, independent individual.
Q3. Describe the journey of a pollen grain from the stigma to the ovule in a flower.
Answer:
After landing on a compatible stigma, the pollen grain absorbs moisture and nutrients and begins to germinate, growing a thin tube called the pollen tube.
This pollen tube grows down through the style, carrying the male gamete with it. The tube produces enzymes to digest the tissues of the style, clearing a path.
The pollen tube eventually enters the ovule, allowing the male gamete to reach and fuse with the female gamete (egg) for fertilization.
Q4. State three functions of the placenta in the human female.
Answer:
The placenta performs three crucial functions during pregnancy:
Nutrition: It facilitates the passage of nutrients like glucose and amino acids from the mother's blood to the developing foetus.
Respiration: It allows oxygen to pass from the mother to the foetus and carbon dioxide to pass from the foetus to the mother.
Excretion: It transports metabolic waste products, such as urea, from the foetal blood to the mother's blood for removal.
Q5. What is puberty? List two changes that are common to both boys and girls during this time.
Answer:
Puberty is the period during adolescence when the reproductive system becomes functional, and secondary sexual characteristics develop, making a person capable of reproduction.
Two changes common to both boys and girls are:
Growth of thick hair in the armpits and genital area.
The skin becomes oily, which may lead to the development of pimples.
Q6. Differentiate between asexual and sexual reproduction. (3 points)
Answer:
| Asexual Reproduction | Sexual Reproduction |
| It involves only one parent. | It involves two parents (male and female). |
| Gametes are not formed. | Gametes (sperm and egg) are formed. |
| Offspring are genetically identical to the parent. | Offspring are genetically different from both parents, showing variation. |
Q7. Explain two methods of artificial vegetative propagation in plants.
Answer:
Two artificial methods are:
Cutting: A piece of the stem or branch having some buds on it is cut from the parent plant. This cutting is planted in moist soil, which develops roots and grows into a new plant. This is commonly used for roses and sugarcane.
Grafting: The stem (scion) of a desired plant is attached to the rooted stem (stock) of another plant. The tissues of the stock and scion join together to form a single plant that has the characteristics of the scion (e.g., better fruit). This is used for mangoes and apples.
Q8. What is the menstrual cycle? What happens during this cycle if the egg is not fertilized?
Answer:
The menstrual cycle is a series of cyclic changes that occur in the reproductive organs of a non-pregnant female every 28-30 days.
If the egg is not fertilized:
The unfertilized egg dies within a day.
The thick and soft lining of the uterus, which was prepared to receive a fertilized egg, is no longer needed.
This lining breaks down and is discharged from the body through the vagina along with blood and mucous. This flow is called menstruation.
Q9. Why is sexual reproduction considered superior to asexual reproduction for the survival of a species?
Answer:
Sexual reproduction is considered superior for the survival of a species for three main reasons:
Promotes Variation: It combines DNA from two different parents, creating new combinations of genes and leading to genetic variation in the offspring.
Adaptability: This variation allows a species to adapt better to changes in the environment. Some individuals will likely have traits that allow them to survive and reproduce in new conditions.
Evolution: It is the basis for evolution, as natural selection acts on these variations, leading to the development of new, better-adapted species over time.
Q10. Draw the human female reproductive system and label the following parts: (i) Ovary (ii) Oviduct (iii) Uterus.
Answer:
Q11. List three methods of contraception and briefly explain how they work.
Answer:
Three methods of contraception are:
Barrier Methods (e.g., Condoms): These physically prevent sperm from reaching the egg, thus preventing fertilization. They also protect against STDs.
Chemical Methods (e.g., Oral Pills): These contain hormones that stop the ovaries from releasing eggs (ovulation), so there is no egg to be fertilized.
Surgical Methods (e.g., Vasectomy/Tubectomy): These are permanent methods. In males (vasectomy), the vas deferens is blocked to prevent sperm release. In females (tubectomy), the fallopian tubes are blocked to prevent the egg from reaching the uterus.
Q12. What are the functions of the testes, seminal vesicles, and prostate gland in the human male?
Answer:
Testes: They produce the male gametes (sperm) and secrete the male sex hormone, testosterone, which is responsible for secondary sexual characteristics.
Seminal Vesicles and Prostate Gland: These are accessory glands. They produce and secrete fluids that mix with the sperm to form semen. This fluid provides nutrition to the sperm and makes their transport easier.
Q13. How does the embryo get nourishment inside the mother's body?
Answer:
The embryo gets nourishment through a special disc-like tissue called the placenta, which is embedded in the uterine wall.
The placenta has villi on the embryo's side and blood spaces on the mother's side, creating a large surface area for exchange.
Nutrients, oxygen, and antibodies pass from the mother's blood into the embryo's blood through the placenta.
The embryo is connected to the placenta by the umbilical cord.
Q14. What are the advantages of spore formation in an organism like Rhizopus?
Answer:
Spore formation offers three key advantages:
Survival: Spores have a thick, protective wall that allows them to survive harsh environmental conditions like high temperatures, lack of water, and acidity.
Dispersal: Spores are very light and can be easily dispersed by wind, water, or animals over large distances, helping the organism colonize new habitats.
Large Numbers: A single sporangium produces thousands of spores, increasing the chances of the species' survival and propagation.
Q15. Draw the human male reproductive system and label the following parts: (i) Testis (ii) Vas deferens (iii) Urethra.
Answer:
Q16. What are secondary sexual characters? List two in boys and two in girls.
Answer:
Secondary sexual characters are the features that appear during puberty that distinguish males from females but are not directly part of the reproductive system.
In Boys: (i) Growth of facial hair (moustache and beard), (ii) Deepening of the voice.
In Girls: (i) Development of breasts, (ii) Broadening of the hips.
Q17. Explain the process of fragmentation in Spirogyra with a diagram.
Answer:
Fragmentation is a common mode of asexual reproduction in simple multicellular organisms like the alga Spirogyra.
The long, filamentous body of the mature Spirogyra breaks up into two or more smaller pieces called fragments.
This breaking can occur naturally upon maturation or due to mechanical disturbance.
Each of these fragments then grows into a new, complete Spirogyra filament.
Q18. Why is it important to use contraceptive methods? Give three reasons.
Answer:
Using contraceptive methods is important for three main reasons:
Preventing Unwanted Pregnancies: It allows individuals and couples to plan their families and decide the timing and number of children they want to have.
Population Control: On a larger scale, it helps in managing the population of a country, reducing the strain on natural resources.
Preventing STDs: Barrier methods like condoms are effective in preventing the transmission of sexually transmitted diseases like HIV-AIDS, syphilis, and gonorrhoea.
Q19. What changes occur in a flower after fertilization?
Answer:
After fertilization, several significant changes occur in the flower:
The ovary enlarges and develops into the fruit.
The ovules inside the ovary develop into seeds.
The petals, sepals, stamens, style, and stigma usually wither and fall off as their functions are complete.
Q20. What is DNA? Why is the creation of a DNA copy a basic event in reproduction?
Answer:
DNA (Deoxyribonucleic acid) is the hereditary material in organisms that carries the genetic instructions for development, functioning, growth, and reproduction.
Creating a DNA copy is a basic event because:
It ensures that the genetic information is accurately passed from the parent cell to the daughter cells.
This transfer of the "blueprint" of life maintains the characteristics of the species in the offspring.
The process, while consistent, allows for minor errors, which are the source of variations crucial for evolution.
Q21. What is tissue culture? Mention two advantages of this technique.
Answer:
Tissue culture (or micropropagation) is an advanced technique of vegetative propagation where new plants are grown from a small piece of parent tissue or a group of cells in a sterile, artificial nutrient medium.
Two advantages are:
Rapid Production: A large number of plants can be grown from a very small amount of parent tissue in a short time.
Disease-Free Plants: It can be used to grow plants that are free from viruses and other diseases, even if the parent plant is infected (by using the meristematic tip).
Q22. Explain the role of the uterus and fallopian tubes in the female reproductive system.
Answer:
Fallopian Tubes (Oviducts): These are a pair of tubes connecting the ovaries to the uterus. Their primary role is to be the site of fertilization. They pick up the egg released from the ovary and provide the environment where it can fuse with a sperm.
Uterus: This is a muscular, pear-shaped organ. Its main role is to nurture the fertilized egg. The embryo implants into the thick uterine wall, and the uterus expands to house the developing foetus throughout the pregnancy.
Q23. Differentiate between pollen and ovules.
Answer:
| Pollen Grains | Ovules |
| They are the male gametophytes of a plant. | They are the female gametophytes of a plant. |
| They are produced in the anther of the stamen. | They are produced in the ovary of the pistil. |
| They contain the male gamete. | They contain the female gamete (egg cell). |
Q24. What is germination? List the conditions necessary for a seed to germinate.
Answer:
Germination is the process by which a dormant seed begins to sprout and grow into a young plant or seedling.
Three essential conditions for germination are:
Water: To activate enzymes and soften the seed coat.
Oxygen: For aerobic respiration to provide energy for growth.
Suitable Temperature: An optimal temperature range is needed for the enzymes within the seed to function effectively.
Q25. How do Amoeba and Leishmania reproduce? How do they differ in their method?
Answer:
Both Amoeba and Leishmania reproduce asexually by the process of binary fission, where a single parent cell divides into two daughter cells.
The key difference lies in the plane of fission:
In Amoeba, which is asymmetrical, division can occur in any plane.
In Leishmania, which has a whip-like structure at one end, division occurs in a definite, longitudinal plane with respect to that structure.
Q26. What is pollination? Differentiate between the characteristics of wind-pollinated and insect-pollinated flowers.
Answer: Pollination is the act of transferring pollen grains from the male anther of a flower to the female stigma.
| Wind-Pollinated Flowers | Insect-Pollinated Flowers |
| They have small, dull petals and are inconspicuous. | They have large, brightly coloured petals to attract insects. |
| They do not produce nectar or scent. | They produce nectar and have a sweet scent. |
| They produce large quantities of light, dry pollen. | They produce smaller quantities of sticky or spiny pollen. |
Q27. Draw a diagram to show binary fission in Amoeba and label the parent cell and daughter cells.
Answer: Binary fission in Amoeba is a method of asexual reproduction.
The parent Amoeba cell first grows to its full size.
The nucleus lengthens and divides into two nuclei (karyokinesis).
The cytoplasm then divides into two parts, each part receiving a nucleus (cytokinesis).
Finally, two smaller, identical daughter Amoebae are formed.
Q28. What is the role of testosterone in human males and oestrogen in human females?
Answer:
Testosterone (in males): It is the primary male sex hormone produced by the testes. Its functions are:
Regulating the formation of sperm.
Bringing about secondary sexual characteristics in boys during puberty, like the growth of facial hair and deepening of the voice.
Oestrogen (in females): It is the primary female sex hormone produced by the ovaries. Its functions are:
Regulating the development and release of the egg (ovum).
Bringing about secondary sexual characteristics in girls, like the development of breasts and mammary glands.
Q29. A woman is using a copper-T. Will it protect her from sexually transmitted diseases? Why?
Answer: No, a copper-T will not protect a woman from sexually transmitted diseases (STDs).
Reason: A copper-T is an Intra-Uterine Contraceptive Device (IUCD) that is placed inside the uterus. It prevents pregnancy by preventing the implantation of the embryo in the uterine wall.
It does not create any physical barrier to prevent the exchange of body fluids during sexual contact. STDs are transmitted through this fluid exchange, so only barrier methods like condoms can offer protection against them.
Q30. Explain how a zygote develops into a foetus in the human female reproductive system.
Answer:
After fertilization in the fallopian tube, the single-celled zygote is formed.
The zygote immediately begins to divide repeatedly (a process called cleavage) as it travels down the fallopian tube, forming a ball of cells called an embryo.
This embryo continues to grow and eventually implants itself into the thick lining of the uterus.
Once implanted, the embryo continues to develop, and body features like hands, legs, head, and eyes begin to form. When the embryo becomes recognisable as a human offspring, it is called a foetus
Take a deep breath and feel proud of your progress. Next up, we're tackling the final boss of questions: the 5-mark Long Answer Questions! You are more than ready for the challenge.
Keep shining! 🌟
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