Olympiad Test: Reproduction In Plants -2 - Class 7 MCQ

Style belongs to:
- A: Pistil
- B: Stamen
- C: Both
- D: None of these
Explanation:
- The style is a part of the pistil, which is the female reproductive organ of a flower.
- The pistil consists of three main parts: the stigma, style, and ovary.
- The style is a slender, elongated tube-like structure that connects the stigma to the ovary.
- Its primary function is to provide support for the stigma and facilitate the fertilization process.
- The style plays a crucial role in pollen tube growth and the delivery of pollen grains to the ovary for fertilization.
- Therefore, the correct answer is A: Pistil.

Scattering of seeds over a wide area is called dispersal.
Explanation:
Dispersal is the process by which seeds are spread or scattered over a wide area. It is an important mechanism for plants to ensure their survival and colonize new habitats. Here is a detailed explanation of seed dispersal:
1. Definition: Dispersal refers to the movement or spreading of seeds away from the parent plant to different locations.
2. Methods of dispersal: Seeds can be dispersed by various means, including:
- Wind: Some seeds are light and have adaptations like wings or hairs that allow them to be carried away by the wind. Examples include dandelions and maple trees.
- Water: Seeds can be transported by water bodies such as rivers, streams, and oceans. They are often buoyant and can survive long distances. Coconuts and water lilies are examples of seeds dispersed by water.
- Animals: Seeds can attach to the fur or feathers of animals and be carried to new areas. Some fruits are consumed by animals, and the seeds pass through their digestive system before being excreted. This helps in seed dispersal. Examples include burrs and berries.
- Gravity: Some seeds fall to the ground due to their weight or by the action of gravity. They may roll or bounce away from the parent plant, ensuring dispersal. Acorns and chestnuts are examples of seeds dispersed by gravity.
3. Importance of dispersal: Seed dispersal is crucial for plant survival and biodiversity for several reasons:
- It prevents overcrowding and competition among plants of the same species.
- It allows plants to colonize new habitats and expand their range.
- It helps in the establishment of new populations and increases gene flow.
- It reduces the risk of diseases and pests affecting all plants of the same species in one location.
In conclusion, the scattering of seeds over a wide area is called dispersal. This process is essential for plants to ensure their survival, reproduce, and colonize new environments.

The seeds of balsam fruit are dry and dispersed by explosion due to the touch of our hands. The walls of the fruit coil inwards, creating forces that throws the seeds to a distance. 

Seed with thick fibrous outer covering:
The correct answer is coconut.
Here is a detailed explanation:
1. Coconut:
- The coconut is a seed with a thick fibrous outer covering, known as the husk or the coconut shell.
- The husk of the coconut is composed of thick fibers that provide protection to the seed inside.
- The fibrous outer covering of the coconut makes it unique and easily recognizable.
- The husk of the coconut is typically brown in color and has a rough texture.
2. Lime:
- The lime is a small citrus fruit and does not have a thick fibrous outer covering like a coconut.
- The lime has a thin, smooth peel that can easily be removed.
3. Papaya:
- The papaya is a fruit that has a soft, fleshy outer covering, not a thick fibrous one like a coconut.
- The skin of a papaya is thin and smooth, similar to other fruits.
4. Neem:
- The neem is a tree that produces a fruit with a thin outer covering, not a thick fibrous one like a coconut.
- The neem fruit has a smooth skin that is usually green or yellow in color.
In conclusion, the seed with a thick fibrous outer covering is the coconut (Option B). The coconut's husk provides protection and gives it a unique appearance compared to other seeds.

The life cycle of a plant consists of the following stages:
1. Seed:
- The life cycle begins with a seed, which contains the embryo of the plant.
- Seeds are typically dispersed by wind, water, or animals.
- They can remain dormant until conditions are favorable for germination.
2. Germination:
- When a seed is exposed to favorable conditions such as moisture, warmth, and oxygen, it undergoes germination.
- The seed absorbs water and swells, causing the protective coat to split.
- The embryonic root, called the radicle, emerges first, followed by the shoot.
3. Seedling:
- The emerging shoot develops into a seedling, which is characterized by the presence of cotyledons (seed leaves).
- The cotyledons provide nutrients to the developing plant until it can photosynthesize on its own.
- The seedling grows roots to anchor itself in the soil and absorb water and nutrients.
4. Sapling:
- As the seedling continues to grow, it develops into a sapling.
- The sapling undergoes significant growth in terms of height and width.
- It continues to develop leaves and branches, increasing its photosynthetic capacity.
5. Plant:
- The sapling eventually matures into a full-grown plant.
- The plant is capable of reproducing through flowers and producing seeds.
- It plays a vital role in the ecosystem by providing shelter and food for other organisms.
Therefore, the correct sequence of the life cycle of a plant is: seed, seedling, sapling, plant.

Seeds with hooks are dispersed by animals
Explanation:
- Seeds with hooks have structures that enable them to attach to the fur, feathers, or clothing of animals.
- These seeds have adaptations such as barbs, spines, or hooks that catch onto the animal's body.
- The animal then unintentionally carries the seeds to different locations, helping in their dispersal.
- Some examples of seeds with hooks that are dispersed by animals include burdock, cocklebur, and bur marigold.
- Animals play a crucial role in the dispersal of seeds with hooks, as they can travel long distances and reach new habitats.
- The seeds can also be dispersed by animals through their droppings, as they may eat the fruits or seeds and excrete them in a different location.
- This method of dispersal increases the chances of the seeds finding suitable conditions for germination and growth.
- Dispersal by animals is particularly important in environments where wind or water dispersal is limited.
- Overall, animals play a vital role in the dispersal of seeds with hooks, contributing to the survival and distribution of various plant species.

The correct answer to this question is d. ovules. When you cut an ovary of a mustard flower, you will see its ovules. Let's break down the solution into bullet points to provide a detailed explanation:
Key Points:
- Mustard flowers are part of the Brassicaceae family and are known for their distinct yellow flowers.
- Like many other flowers, mustard flowers also have reproductive structures, including ovaries.
- The ovary is the swollen base of the pistil, which is the female reproductive organ of a flower.
- Inside the ovary, you can find ovules, which are the structures that develop into seeds after fertilization.
- Cutting the ovary of a mustard flower will expose the ovules, allowing you to observe them.
- Ovules contain the female reproductive cells and are essential for plant reproduction and seed formation.
To summarize, when you cut an ovary of a mustard flower, you will see the ovules. These ovules are responsible for seed production and are crucial in the reproductive process of the plant.

Embryonic Development

In embryology, the development of an organism from a single-celled zygote to a complex multicellular organism involves several stages. One of the important stages is the development of the embryo, which is the early stage of growth and differentiation of the organism.

Zygote

• The zygote is the initial cell formed when a sperm fertilizes an egg.


• It contains all the genetic information necessary for the development of the organism.


• The zygote undergoes various cellular divisions and transformations to develop into an embryo.


• During this process, the zygote forms different layers of cells that will eventually give rise to different tissues and organs.

Embryo

• The embryo is the stage of development after the zygote.


• It is characterized by rapid cell division and differentiation.


• During embryonic development, the cells continue to divide and specialize to form different structures and organs of the organism.


• Specifically, the embryo develops structures such as the nervous system, cardiovascular system, limbs, and organs.


• As the embryo grows and develops, it eventually becomes a fetus.

Therefore, the correct answer to the given question is Option B: Zygote. The zygote develops into an embryo during embryonic development.

Rose and Champa Reproduction Methods:

1. Grafting: This method involves joining a stem (scion) of one plant to the root system (rootstock) of another plant. It is commonly used for propagating rose and champa plants with desirable traits.


2. Root Cutting: This method involves cutting a section of the root of a plant and allowing it to grow into a new plant. However, rose and champa plants are not typically reproduced through root cutting.


3. Layering: Layering is a method where a branch of the plant is bent and partially buried in the soil, allowing it to develop roots. Once the roots are established, the branch can be separated and grown as a new plant. Rose and champa plants can be propagated successfully through layering.


4. Stem Cutting: Stem cutting is a common method of propagation for many plants, including roses and champa. It involves taking a cutting from the stem of the plant, usually with a few leaf nodes, and planting it in a suitable growing medium. The cutting will develop roots and grow into a new plant.

Therefore, the correct answer is option D: Stem cutting. Rose and champa plants reproduce through stem cuttings.