NCERT Solutions for Class 10 How Do Organisms Reproduce: NCERT books are considered the best source for preparation of theoretical concepts and making the basics strong. The questions provided in NCERT textbooks at the end of each chapter and intext question are quite important for examination point of view and for better understanding of the concepts. It is highly recommended to follow the NCERT Textbook for the exam.
In this article you will find all the NCERT intext and final exercise solutions for CBSE Class 10 Science Chapter 7, How Do Organisms Reproduce. All the class 10 Science NCERT solutions have been collated in PDF format which students may easily download free of cost.
Check NCERT Solutions for CBSE Class 10 Science Biology Chapter 7 How Do Organisms Reproduce below:
Intext Solution Page No. -114
1) What is the importance of DNA copying in reproduction?
DNA copying is crucial in reproduction because it makes sure that offspring get the correct set of instructions from their parents. This process ensures that the new generation has the same genetic information as the previous one, allowing traits to be passed on correctly. Accurate DNA copying is essential for healthy development and function, and it helps maintain consistency and stability in living organisms.
2) Why is variation beneficial to the species but not necessarily for the individual?
Variation is beneficial to a species because it helps the group adapt to changes in the environment, which can improve survival over time.
For example-
For the species: If some people can swim, some can walk on stones, and others can use a raft, the group has a better chance of crossing safely. This variety increases the group's chances of survival.
For an individual: If you can only swim, and the river is full of stones, you might not make it. This shows that a specific skill might not be helpful in every situation for an individual.
Intext Solution Page No. -119
1) How does binary fission differ from multiple fission?
Binary fission and multiple fission are both types of asexual reproduction found in single-celled organisms. The main difference lies in the number of daughter cells produced.
Binary Fission
- One cell divides into two identical daughter cells.
- Think of it like splitting a ball into two equal halves.
- Example: Bacteria, Amoeba
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Multiple Fission
- One cell divides into many daughter cells at once.
- Imagine a ball splitting into many smaller balls.
- Example: Plasmodium (malaria parasite)
2) How will an organism be benefited if it reproduces through spores?
Reproducing through spores can be very beneficial for organisms in several ways:
- Survival in Tough Conditions: Spores are often very resistant to harsh conditions like extreme temperatures, dryness, or lack of nutrients. This helps the organism survive in environments where other forms of reproduction might not work.
- Wide Spread: Spores can be spread easily by the wind, water, or animals. This allows the organism to colonize new areas far from where it originally lived, increasing its chances of finding a suitable place to grow.
- Rapid Reproduction: Spores can grow into new organisms quickly once they land in a suitable environment, which helps the organism reproduce and grow faster than some other methods.
3) Can you think of reasons why more complex organisms cannot give rise to new individuals through regeneration?
Complex organisms typically cannot reproduce through regeneration because their bodies are much more intricate and specialized compared to simpler organisms. These organisms have complex structures and systems, such as organs and tissues, that work together in a precise way. Regenerating a complete organism from a single body part would be difficult because it would require recreating all these specialized systems perfectly. While some complex organisms can regrow certain parts, like a lizard regrowing its tail, they cannot generate a whole new organism from just one piece of their body.
4) Why is vegetative propagation practiced for growing some types of plants?
Vegetative propagation is practiced for growing some types of plants because it offers several advantages:
- This method produces new plants that are genetically identical to the parent plant. This is useful for maintaining specific traits or qualities, such as fruit flavor or flower color.
- Vegetative propagation often allows plants to grow more quickly compared to starting from seeds. It can be faster because it skips the seed stage and directly produces new plants.
- Some plants may not grow well from seeds due to environmental conditions or other factors. Vegetative propagation can be more reliable in these cases.
- This method helps preserve desirable traits of the parent plant, such as disease resistance or high yield, which might not be consistently passed on through seeds.
5) Why is DNA copying an essential part of the process of reproduction?
DNA copying is an essential part of reproduction for several key reasons:
- DNA carries the instructions for an organism's traits. Copying DNA ensures that these instructions are passed accurately to the offspring, so they inherit the same traits as their parents.
- During reproduction, cells need to divide to form new individuals. DNA copying ensures that each new cell gets a complete set of instructions, which is crucial for the proper development of the new organism.
- Accurate DNA copying helps prevent errors that could lead to health problems or developmental issues in the offspring.
- DNA copying allows traits and characteristics to be passed from one generation to the next, contributing to the continuity and stability of species.
Intext Solution Page No. - 126
1) How is the process of pollination different from fertilisation?
Pollination and fertilization are two different steps in plant reproduction:
- Pollination: This is the process where pollen (which contains male gametes) is transferred from the male part of a flower (anther) to the female part (stigma) of the same or another flower. Pollination can happen through wind, insects, or animals. It’s like delivering a letter with important instructions to the right address.
- Fertilization: After pollination occurs, fertilization is the next step where the pollen travels down to the ovule in the flower’s ovary and joins with the egg cell (female gamete). This joining of pollen and egg forms a seed. Fertilization is like the actual writing of a new document based on the instructions received.
2) What is the role of the seminal vesicles and the prostate gland?
The seminal vesicles and the prostate gland play important roles in male reproduction:
Seminal Vesicles: These are glands that produce a fluid that nourishes and helps transport sperm. This fluid makes up a significant portion of the semen, which provides energy to sperm and helps them move more effectively.
Prostate Gland: The prostate gland produces another fluid that also becomes part of the semen. This fluid helps to protect and activate sperm, making them more effective in reaching and fertilizing an egg.
3) What are the changes seen in girls at the time of puberty?
These changes mark the transition from childhood to adulthood and are part of normal physical and hormonal development during puberty:
- Menstruation: Start of menstrual periods.
- Changes in Body Shape: Widening of hips and more body curves.
- Breast Development: Formation and growth of breasts.
- Growth Spurts: Rapid increase in height.
- Pubic and Underarm Hair: Growth of hair in these areas.
- Skin Changes: Increase in oil production, possible acne.
- Emotional Changes: Mood swings and emotional sensitivity.
4)How does the embryo get nourishment inside the mother’s body?
The embryo gets nourishment inside the mother’s body through the placenta. Here’s how it works:
Placenta Formation: After implantation, the embryo forms a special organ called the placenta, which connects to the mother’s uterus.
Nutrient Exchange: The placenta allows nutrients and oxygen from the mother’s blood to pass into the embryo. It also helps remove waste products from the embryo’s blood.
Umbilical Cord: The placenta is connected to the embryo by the umbilical cord. This cord carries the nutrients and oxygen from the placenta to the embryo and returns waste products back to the placenta.
5) If a woman is using a copper -T, will it help in protecting her from sexually transmitted diseases?
No, a Copper-T (an intrauterine device or IUD) does not protect against sexually transmitted diseases (STDs). It is designed to prevent pregnancy by stopping the sperm from reaching the egg. To protect against STDs, it’s important to use protective methods, which provides a barrier that helps prevent the spread of infections.
EXERCISES
- Asexual reproduction takes place through budding in
(a) Amoeba.
(b) Yeast.
(c) Plasmodium.
(d) Leishmania.
(b) Yeast.
- Which of the following is not a part of the female reproductive system in human beings?
(a) Ovary
(b) Uterus
(c) Vas deferens
(d) Fallopian tube
(c) Vas deferens
- The anther contains
(a) sepals.
(b) ovules.
(c) pistil.
(d) pollen grains.
(d) Pollen grains
- What are the advantages of sexual reproduction over asexual reproduction?
Sexual reproduction has several advantages over asexual reproduction:
Genetic Diversity: Sexual reproduction mixes the genes of two parents, creating offspring with unique combinations of traits. This diversity helps species adapt to changing environments and improves chances of survival.
Disease Resistance: With genetic diversity, offspring are less likely to all be affected by the same diseases or pests. This helps in building stronger populations.
Evolution: Sexual reproduction speeds up evolution by introducing new traits and variations, which can lead to better adaptation and evolution of the species.
- What are the functions performed by the testis in human beings?
The testis in human beings performs two main functions:
Sperm Production: The testis produces sperm, which are the male reproductive cells needed for fertilizing an egg during reproduction.
Hormone Production: The testis also makes a hormone called testosterone, which is important for developing male characteristics like facial hair and a deep voice, and for maintaining sexual health.
- Why does menstruation occur?
Menstruation occurs as part of the monthly cycle of changes in a woman's body. Here's why it happens:
- Every month, the uterus prepares to support a potential pregnancy by building up a thick lining. This lining is rich in blood vessels and nutrients.
- If the egg released during ovulation isn’t fertilized by sperm, there is no pregnancy. The body no longer needs the thick lining of the uterus.
- To get rid of the unnecessary lining, the uterus sheds it through the vagina. This shedding is what we see as menstrual bleeding.
- Draw a labelled diagram of the longitudinal section of a flower.
Labels:
Ovary: The part of the flower that contains ovules (egg cells) and becomes the fruit after fertilization.
Style: The tube that connects the stigma to the ovary.
Stigma: The part where pollen grains land and germinate.
Anther: The part of the stamen that produces pollen.
Filament: The stalk that supports the anther.
- What are the different methods of contraception?
Find the different methods of contraception below:
Barrier Methods:
- Condoms: Worn on the penis (male condom) or inside the vagina (female condom) to prevent sperm from entering the uterus.
- Diaphragm: A dome-shaped device placed inside the vagina to block sperm from reaching the uterus.
Hormonal Methods:
- Birth Control Pills: Pills taken daily to prevent ovulation (release of an egg) and alter the lining of the uterus.
- Contraceptive Patches: Patches worn on the skin that release hormones to prevent pregnancy.
- Hormonal Injections: Shots given every few months that release hormones to stop ovulation.
- Birth Control Implants: Small rods placed under the skin that release hormones to prevent pregnancy.
Intrauterine Devices (IUDs):
- Copper IUD: A small device inserted into the uterus that prevents sperm from fertilizing an egg.
- Hormonal IUD: Releases hormones to prevent pregnancy and can also make periods lighter
- How are the modes for reproduction different in unicellular and multicellular organisms?
In unicellular and multicellular organisms, reproduction happens in different ways:
- Unicellular Organisms:
- Asexual Reproduction: Most unicellular organisms, like bacteria and amoebas, reproduce by a process called asexual reproduction. This often involves binary fission, where the cell splits into two identical new cells. This process is simple and quick, and the new cells are exact copies of the original.
- Multicellular Organisms:
- Asexual Reproduction: Some multicellular organisms, like plants and certain animals, can also reproduce asexually. They might use methods like budding (new individuals grow from parts of the parent) or vegetative propagation (new plants grow from parts of the parent plant, like roots or stems).
- Sexual Reproduction: Many multicellular organisms reproduce sexually, which involves combining the genetic material from two parents. This process includes fertilization, where male and female reproductive cells join to form a new, unique organism. Sexual reproduction creates diversity and helps organisms adapt to changing environments.
- How does reproduction help in providing stability to populations of species?
Reproduction helps in providing stability to populations of species in several ways:
- Regular reproduction ensures that new individuals are born to replace older or dying members of a species, keeping the population stable over time.
- Sexual reproduction creates varied offspring with different traits. This diversity helps the species adapt to changes in the environment, such as new diseases or climate changes, increasing the chances of survival.
- By producing new generations with different combinations of traits, reproduction helps the species evolve and improve over time, making it more resilient to challenges.
- What could be the reasons for adopting contraceptive methods?
People adopt contraceptive methods for several important reasons:
- Contraceptives help avoid pregnancy when people are not ready or do not wish to have children at that time.
- They allow people to plan when to have children and how many they want, helping to manage family and financial resources better.
- Some people use contraceptives for health reasons, such as to manage menstrual cycles or reduce the risk of certain health conditions.
- Contraceptives help in spacing pregnancies, allowing time for recovery and better preparation for future children.
- In some cases, pregnancy could pose a health risk to the mother or baby, and contraceptives help avoid these risks.
To download these solutions in PDF format, click on the link below:
Download NCERT Class 10 Science Chapter 7 How do Organisims Reproduce Solution Manual PDF
These solutions follows the latest CBSE Class 10 Science syllabus 2024-25 and the updates NCERT textbook thus, do not include the deleted topics.
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