- A. Bryophyllum
- B. Fungi
- C. Virus
- D. Bacteria
(a) Bryophyllum
- A. Spore formation
- B. Fragmentation
- C. Pollination
- D. Budding
(d) Budding
- A. Root
- B. Stem
- C. Leaf
- D. Flower
(d) Flower
- A. Wind
- B. Water
- C. Insect
- D. All the above
d) All the above
- A. Betel
- B. Black pepper
- C. Both of them
- D. None of them
(c) Both of them
Androecium
Ovary
seed
mangrove
Bulb
True. A complete flower has four whorls, which are concentric rings of floral parts arranged around the receptacle. These four whorls are the calyx (sepals), corolla (petals), androecium (stamens), and gynoecium (carpels). Each whorl has a specific function in the reproduction and protection of the flower. The calyx protects the flower bud, the corolla attracts pollinators, the androecium produces pollen, and the gynoecium contains the ovules for seed production.
True. The transfer of pollen to the stigma is known as pollination. Pollination is an essential process in plant reproduction where pollen grains from the anther of a flower are transferred to the stigma of the same flower or another flower. This transfer can occur through various agents such as insects, wind, water, and animals. Once pollen reaches the stigma, it germinates and grows a pollen tube that allows fertilization to occur, leading to seed and fruit formation.
True. The carrot has a conical shaped root. This type of root is called a taproot, which is a modified root that stores food and water. The conical or tapering shape of the carrot root allows it to penetrate deep into the soil to absorb water and nutrients. The carrot root is swollen and fleshy because it accumulates and stores carbohydrates and other nutrients, making it edible and nutritious for human consumption.
False. The correct statement is that ginger is an underground stem, not a root. Ginger is a rhizome, which is a horizontal underground stem that grows beneath the soil surface. Although it appears root-like and is found underground, it has the characteristics of a stem, including nodes and internodes where buds can develop into new shoots. This is why ginger can be propagated by planting pieces of the rhizome, and new plants will grow from the buds present on these stem segments.
True. The leaves of Aloe vera are fleshy and store water. Aloe vera is a succulent plant that has adapted to survive in dry and arid environments by storing large quantities of water in its thick, fleshy leaves. This water storage allows the plant to survive long periods without rainfall. The leaves also contain a gel-like substance that has medicinal properties and is commonly used in skincare and health products. The fleshy nature of the leaves is an adaptation that helps the plant conserve water and thrive in harsh desert conditions.
The two types of reproduction in plants are sexual reproduction and asexual reproduction. Sexual reproduction involves the fusion of male and female gametes, resulting in the formation of seeds that contain genetic material from both parents. This type of reproduction occurs through pollination and fertilization in flowering plants. Asexual reproduction does not involve the fusion of gametes and produces offspring that are genetically identical to the parent plant. Asexual reproduction can occur through vegetative propagation methods such as runners, tubers, bulbs, fragmentation, and budding.
The two important parts of a flower are the androecium and the gynoecium. The androecium is the male reproductive part of the flower, consisting of stamens that produce pollen grains. Each stamen has an anther where pollen is produced and a filament that supports the anther. The gynoecium is the female reproductive part of the flower, consisting of the carpel or pistil. The carpel contains the stigma that receives pollen, the style that connects the stigma to the ovary, and the ovary that contains ovules. These two parts are essential for sexual reproduction in flowering plants.
Pollination is the transfer of pollen grains from the anther of a flower to the stigma of the same flower or another flower of the same species. This is a crucial step in plant sexual reproduction that must occur before fertilization can take place. Pollination can be self-pollination, where pollen from a flower pollinates the stigma of the same flower, or cross-pollination, where pollen is transferred between different flowers. The process is facilitated by various agents including insects, wind, water, and animals, which help carry pollen grains from one flower to another.
The agents of pollination are insects, wind, water, and animals. Insects such as bees, butterflies, and moths visit flowers to collect nectar and pollen, and in the process, they transfer pollen from flower to flower. Wind carries light pollen grains from one flower to another in wind-pollinated plants. Water can transport pollen in aquatic plants and some plants growing near water bodies. Animals such as birds and mammals also help in pollination by visiting flowers for food and inadvertently transferring pollen on their bodies. Each agent is suited to pollinate specific types of flowers based on flower structure and characteristics.
- A. Corm
- B. Tuber
Corm-e.g Colocasia
Tuber – e.g Potato.
Bisexual flowers and unisexual flowers differ in their reproductive structure and pollination requirements. A bisexual flower contains both the male reproductive part (androecium) and the female reproductive part (gynoecium) in the same flower, such as in hibiscus. Because bisexual flowers have both male and female parts, they can undergo both self-pollination, where pollen from the anther pollinates the stigma of the same flower, and cross-pollination, where pollen is transferred to another flower. An unisexual flower contains only either the androecium or the gynoecium, but not both. Unisexual flowers can only be pollinated through cross-pollination because they lack either the male or female reproductive part. Examples of unisexual flowers include papaya, where separate male and female flowers exist on different plants or different parts of the same plant. This difference in flower structure affects how these plants reproduce and the genetic diversity of their offspring.
Cross pollination is the transfer of pollen grains from the anther of one flower to the stigma of another flower of the same species or kind, which may be on the same plant or a different plant. In cross pollination, pollen must be transported from one flower to another, requiring external agents to facilitate the transfer. Plants that rely on cross pollination typically produce pollen grains in larger quantities to increase the chances that some pollen will successfully reach the stigma of another flower. Cross pollination introduces genetic variations in the characteristics of new plants because the offspring receive genetic material from two different parent plants, resulting in greater genetic diversity compared to self-pollination. Cross pollination is brought about by various natural agencies including wind, water, insects, and animals. Wind-pollinated plants like grasses produce light, dry pollen that can be carried long distances. Insect-pollinated plants like apples and plums produce colorful, scented flowers with nectar to attract pollinators such as bees and butterflies. These pollinators visit flowers to collect nectar and pollen, and in the process, they transfer pollen between flowers, facilitating cross pollination.
A phyllode is a modified petiole (leaf stalk) that becomes flattened and leaf-like in appearance and function. In plants like Acacia auriculiformis, the petioles expand and become green to form structures that resemble leaves. These phyllodes carry out the functions normally performed by leaves, particularly photosynthesis. The actual leaves in such plants are either absent or reduced to small scales. Phyllodes are an adaptation that allows plants to reduce water loss while maintaining the ability to photosynthesize, making them particularly useful in plants growing in dry environments.
Transfer of pollen grains from the anther to the stigma is called pollination. There are two types of Pollination.
(a) Self Pollination
(b) Cross Pollination
(a) Self pollination
Pollen grains are transferred from the anther to the stigma of the same flower or to another flower of the same plant.
Plants do not need to produce pollen grains in a large quantity for self pollination.
It does not produce changes in the characteristics of new plants
(b) Cross Pollination
Pollen grains are transferee! for the anther of one flower to the stigma of anoter flower of the same kind or different plant.
Plants need to produce pollen grains in larger quantities to increase the chance of pollination.
Cross pollination does introduce variations in characteristics of new plants, e.g (apples, plums)
Agents like wind, water, insects and animals are helpful for pollination and are known as pollinators.
Wind pollinated plants produce pollen which are light. Insect pollinated flowers are brightly coloured and produce lot of pollen which sticks to the body of insects and are caused to other plants.
Pollination that occurs in nature is called Natural pollination.
Pollination between desired plants can be brought about by artificial methods.
There are some stems that grow under the ground to store food. These underground stems swell and become thick.
There are four types of underground stems:
Rhizome.
Corm
Tuber
Bulb
(i) Rhizome : It is an underground thick stem with nodes and intemodes with scale , leaves at the node. It grows horizontally and has an irregular shape. Rhizome have buds. It gives rise to new stem and leaves. E.g. Ginger and Turmeric.
(ii) Corm: This underground stem is round in shape and flat at the top and bottom. It
is a condensed form of rhizome and bears one or more buds in the axils of scale leaves. Daughter plants arise from their buds. E.g. Colocasia.
(iii) Tuber: It is an enlarged, spherical underground stem that stores food. It has many dormant buds on its surface known as “Eyes”. If we plant a part of tuber with the bud, it grows into a new plant. E.g. Potato.
(iv) Bulb: It is condensed stem which is disc like and stores food in the fleshy leaves. The bulb has two types of leaves.
Fleshy Leaves
Scaly Leaves
The upper part of the stem has a terminal bud and it is covered by many scaly leaves, the inner fleshy leaves store food as seen in Garlic and Onion
Ginger is considered a stem rather than a root because it possesses several characteristic features of a stem. It has scale leaves, which are small leaf-like structures, along with nodes and internodes, which are the segments and spaces between them. Additionally, ginger has axillary buds that arise from the angles between leaves and the main axis, as well as a terminal bud at its tip. These are all typical features of stems. Although ginger grows underground, it is a modified underground stem called a rhizome, not a root. The primary function of ginger is to store food reserves in the form of starch and other nutrients, which allows the plant to survive unfavorable conditions and produce new shoots. This combination of stem characteristics and its underground location with a storage function makes ginger a classic example of a modified stem adaptation.
If pollen grain from a rose flower gets deposited on the stigma of a lily flower, the pollen will not germinate and will be wasted. Pollen germination will not take place because pollen of a flower is compatible only with the stigma of flowers belonging to the same species. This specificity is called reproductive isolation or incompatibility. The stigma of a flower produces chemical substances that recognize and accept only pollen from the same species. When pollen from a different species lands on an incompatible stigma, the stigma does not provide the necessary chemical signals or nutrients required for pollen tube growth and germination. Additionally, the pollen grain wall and the stigma surface have specific molecular recognition systems that must match for successful pollination to occur. This mechanism ensures that cross-pollination between different species does not happen, maintaining the genetic purity of each species and preventing the formation of sterile or unviable hybrid offspring.
- A. Assertion is correct, Reasoning is incorrect
- B. Assertion is incorrect, Reasoning is correct
- C. Assertion is correct, Reasoning is correct
- D. Assertion is incorrect, Reasoning is incorrect
(c) Assertion is correct, Reasoning is correct.
- A. Assertion is incorrect, Reasoning is correct.
- B. Assertion is incorrect, Reasoning is incorrect
- C. Assertion is correct, Reasoning is correct
- D. Assertion is correct, Reasoning is incorrect
(a) Assertion is incorrect, Reasoning is correct.
Name
Modification
1.
Garlic
Underground stem modification
2.
Turnip
Top Root modified for storage (Top shaped)
3.
Rose plant
Stem used for vegetative propagation / Asexual Reproduction by cutting
4.
Maize
Stilt Roots (Adventitious roots produced from the node for mechanical support).