Question:

What is a bisexual flower? Collect five bisexual flowers from your neighbourhood and with the help of your teacher find out their common and scientific names.

Answer:

1. Explain to your teacher what a bisexual flower is. A bisexual flower is a flower that has both male and female reproductive organs, allowing it to self-pollinate.

2. With the help of your teacher, identify five bisexual flowers in your neighbourhood.

3. Collect the five bisexual flowers you’ve identified.

4. With the help of your teacher, find out the common and scientific names of the five bisexual flowers you’ve collected.

5. Record the common and scientific names of the five bisexual flowers you’ve collected.

Question:

What is vegetative propagation? Give two suitable examples.

Answer:

Answer: Vegetative propagation is a type of asexual reproduction in plants, where a new plant is produced from a piece of the parent plant.

Examples of vegetative propagation include:

1. Stem cutting - taking a cutting from a stem and planting it to produce a new plant.
2. Layering - bending a stem of the parent plant so that it touches the ground, and then covering it with soil to produce a new plant.

Question:

Differentiate between a zoospore and a zygote.

Answer:

Step 1: Understand the definitions of zoospore and zygote.

Step 2: Identify the key differences between a zoospore and a zygote.

Step 3: Explain the differences in detail.

A zoospore is a motile asexual spore that is produced by some algae, fungi, and protozoans. It is a single-celled organism that is capable of swimming due to its flagellum.

A zygote is a fertilized egg cell that is formed when two haploid gametes fuse together. It is the first stage of embryonic development and will eventually develop into a multicellular organism.

The main difference between a zoospore and a zygote is that a zoospore is an asexual spore while a zygote is a fertilized egg cell. Additionally, a zoospore is a single-celled organism while a zygote is a diploid cell. Furthermore, a zoospore is capable of swimming due to its flagellum, while a zygote does not have this capability. Lastly, a zoospore is not the first stage of embryonic development, while a zygote is.

Question:

Why are offspring of oviparous animals at a greater risk as compared to offspring of viviparous animals?

Answer:

1. First, we need to understand the difference between oviparous and viviparous animals. Oviparous animals are animals that lay eggs, while viviparous animals are animals that give birth to live young.

2. Offspring of oviparous animals are at greater risk because they are not protected by their mother’s body and are exposed to the environment. This means they are more vulnerable to predators and environmental factors, such as temperature and humidity.

3. In contrast, offspring of viviparous animals are protected by their mother’s body and are provided with nutrients and oxygen from their mother’s circulation. This means they are less vulnerable to predators and environmental factors.

4. Therefore, offspring of oviparous animals are at greater risk as compared to offspring of viviparous animals.

Question:

Why is reproduction essential for organisms?

Answer:

1. Reproduction is essential for organisms because it allows them to produce offspring and continue their species.

2. Without reproduction, a species would eventually become extinct as there would be no new individuals to replace those that die.

3. Reproduction also allows for genetic variation within a species, which is important for its survival in the face of ever-changing environmental conditions.

4. Finally, reproduction is important for maintaining population size, as it ensures that there are enough individuals to sustain the species over time.

Question:

Describe the post-fertilization changes in a flower.

Answer:

1. After fertilization, the flower ovary begins to swell as the ovules inside the ovary begin to develop.

2. The petals of the flower will start to wither and fall off as the ovary continues to swell.

3. The sepals of the flower will start to turn green and become enlarged as the ovary swells.

4. The ovary will eventually become a fruit, containing the seeds that were fertilized.

5. The fruit will mature and eventually become ripe and ready for dispersal.

6. The petals and sepals will fall off the flower, leaving only the fruit behind.

Question:

Why is the offspring formed by asexual reproduction referred to as clone?

Answer:

1. Offspring formed by asexual reproduction is referred to as clone because it is genetically identical to the parent organism.

2. This is because asexual reproduction involves only one parent, and the offspring it produces is a genetic copy of the parent.

3. Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or the exchange of genetic material between two organisms.

4. Instead, a single organism produces offspring that are genetically identical to itself. As a result, the offspring produced by asexual reproduction are referred to as clones.

Question:

Define: (a) Juvenile phase (b) Reproductive phase (c) Senescent phase

Answer:

(a) Juvenile phase: This is the phase of an organism’s life cycle in which it is growing and developing, but has not yet reached reproductive maturity.

(b) Reproductive phase: This is the phase of an organism’s life cycle in which it is capable of reproducing and producing offspring.

(c) Senescent phase: This is the phase of an organism’s life cycle in which it is declining in health and vigor due to age-related changes and is no longer capable of reproducing.

Question:

Which is a better mode of reproduction sexual or asexual? Why?

Answer:

Step 1: Evaluate the pros and cons of both sexual and asexual reproduction.

Step 2: Consider the advantages and disadvantages of each mode of reproduction.

Step 3: Decide which mode of reproduction is best based on your evaluation.

Step 4: Explain your answer. Sexual reproduction is generally considered to be the better mode of reproduction because it allows for genetic diversity and the potential for adaptation to changing environments. Asexual reproduction, on the other hand, is limited and does not allow for genetic variation. This can lead to a population being unable to adapt to changing environments and eventually becoming extinct.

Question:

Distinguish between asexual and sexual reproduction. Why is vegetative reproduction also considered as a type of asexual reproduction?

Answer:

Step 1: Asexual reproduction is a type of reproduction which involves only one parent and produces offspring that are genetically identical to the parent. Sexual reproduction involves two parents and produces offspring that are genetically different from the parents.

Step 2: Vegetative reproduction is a type of asexual reproduction because it involves only one parent and produces offspring that are genetically identical to the parent. Vegetative reproduction involves the use of parts of a plant, such as roots, stems, and leaves, to produce new plants.

Question:

Identify each part in a flowering plant and write whether it is haploid (n) or diploid (2n). (a) Ovary (b) Anther (c) Egg (d) Pollen (e) Male gamete (f) Zygote

Answer:

(a) Ovary - 2n (b) Anther - n (c) Egg - 2n (d) Pollen - n (e) Male gamete - n (f) Zygote - 2n

Question:

Explain why meiosis and gametogenesis are always interlinked?

Answer:

1. Meiosis is a type of cell division that produces four daughter cells with half the number of chromosomes as the parent cell. It is necessary for the production of gametes (sex cells) which contain only one set of chromosomes.

2. Gametogenesis is the process of producing gametes (sex cells) from germ cells. During this process, the germ cells undergo meiosis in order to produce the gametes.

3. Therefore, meiosis and gametogenesis are always interlinked because meiosis is required for the production of gametes, which is the goal of gametogenesis.

Question:

Higher organisms have resorted to sexual reproduction in spite of their complexity. Why?

Answer:

1. Sexual reproduction is beneficial to higher organisms because it increases genetic diversity and allows for the adaptation of a species to changing environmental conditions.

2. Sexual reproduction involves the combining of genetic material from two different individuals, which increases the variety of genetic combinations that can be produced. This allows for the potential for greater diversity among offspring and increases the chances of successful adaptation to new environmental conditions.

3. Furthermore, sexual reproduction allows for the possibility of beneficial mutations to be passed on to future generations. This is because mutations that are beneficial to an organism’s survival are more likely to be passed on, whereas mutations that are detrimental are more likely to be eliminated.

4. Finally, sexual reproduction can also help to ensure the survival of a species by allowing for the formation of new species, which can become better adapted to their environment than their predecessors. This is because new species can form through the combination of different genetic material from two different species, creating a new species that is better adapted to its environment.

Question:

How does the progeny formed from asexual reproduction differ from those formed by sexual reproduction?

Answer:

Step 1: Asexual reproduction is a type of reproduction that only requires one parent and does not involve the fusion of gametes or the exchange of genetic material.

Step 2: Sexual reproduction is a type of reproduction that involves the fusion of gametes from two parents and the exchange of genetic material.

Step 3: The progeny formed from asexual reproduction is genetically identical to the parent, while the progeny formed from sexual reproduction is genetically diverse due to the exchange of genetic material.

Question:

Differentiate gametogenesis from embryogenesis.

Answer:

Step 1: Understand the meaning of the words ‘gametogenesis’ and ’embryogenesis’.

Step 2: Research the processes of gametogenesis and embryogenesis.

Step 3: Compare and contrast the two processes.

Step 4: Identify the key differences between gametogenesis and embryogenesis.

Question:

Define external fertilization. Mention its disadvantages.

Answer:

External fertilization: External fertilization is a type of reproduction in which the eggs and sperm are released into the environment, where they meet and fertilize outside of the body.

Disadvantages of external fertilization:

1. There is a low rate of success in fertilization due to the unpredictable nature of the environment.
2. There is a greater risk of predation on eggs and sperm, as they are exposed to predators in the environment.
3. It is difficult for the parent to ensure that the eggs and sperm meet in the environment.
4. There is a lack of parental care for the eggs and young, as the parents are not present to protect them.

Question:

Examine a few flowers of any cucurbit plant and try to identify the staminate and pistillate flowers. Do you know any other plant that bears unisexual flowers?

Answer:

1. Identify the cucurbit plant you wish to examine.

2. Observe the flowers of the cucurbit plant and look for differences between the staminate and pistillate flowers.

3. Examine a few flowers of the cucurbit plant and try to identify the staminate and pistillate flowers by looking for distinguishing features such as size, shape, and color of the petals.

4. Do you know any other plant that bears unisexual flowers? Yes, other plants that bear unisexual flowers include corn, cotton, and willow trees.

Question:

Offspring formed due to sexual reproduction have better chances of survival. Why? Is this statement always true?

Answer:

Step 1: Offspring formed due to sexual reproduction have better chances of survival because they have a combination of genes from both parents which can make them better adapted to their environment.

Step 2: This statement is not always true. In some cases, the offspring may not have the best combination of genes from both parents and may not be as well adapted to their environment as other offspring.