Mix Examples - How do Organisms Reproduce? Questions in English

(B) Advantages of sexual reproduction:
$1$. In sexual reproduction,more variations are produced due to the combination of $DNA$ from two parents. This genetic diversity ensures the survival of the species in a changing environment.
$2$. The newly formed individual inherits characteristics from both parents,leading to unique combinations of traits.
$3$. Variations are more viable in the sexual mode compared to the asexual mode. In asexual reproduction,the $DNA$ must function within the existing cellular apparatus,limiting the scope for significant evolutionary changes.

(N/A) Living organisms reproduce to ensure the continuation of their species.
Reproduction provides stability to the population of a species by producing new individuals that resemble their parents.
This is the reason why cats give birth to only cats and dogs give birth to only dogs.
By maintaining the characteristics of the species through successive generations,reproduction ensures that the population remains stable and continues to exist in its environment.

(N/A) In sexual reproduction,two individuals having different variations combine their $DNA$ to give rise to a new individual. Therefore,sexual reproduction allows more variations,whereas in asexual reproduction,chance variations can only occur when the copying of $DNA$ is not accurate.
Additionally,asexual reproduction allows for very few variations because if there are too many variations,the resultant $DNA$ may not be able to function within the inherited cellular apparatus.
However,in sexual reproduction,more variations are allowed and the resultant $DNA$ is able to survive,thus making the variations viable.
$Variation$ and $Evolution$: Variants help the species to survive in changing conditions. Environmental factors such as heat,light,pests,and food availability can change suddenly. At such times,only those variants resistant to these conditions are able to survive. This slowly leads to the evolution of a better-adapted species. Thus,variation plays a crucial role in the evolution of sexually reproducing organisms.

(A) Reproduction is a biological process by which living organisms produce new individuals similar to themselves.
It is not necessary for the survival of an individual organism,unlike processes such as respiration,nutrition,or excretion.
Instead,reproduction is essential for the survival of a species,as it ensures the continuity of life by passing on genetic information from one generation to the next.
Therefore,the primary purpose of reproduction is to continue the species generation after generation.

(N/A) Reproduction involves the transfer of $DNA$ from one generation to the next. The process of $DNA$ copying occurs with high consistency,ensuring that the fundamental characteristics of the species are maintained. While minor variations occur during this process,the overall consistency in $DNA$ replication allows a species to maintain its population structure and adapt to its environment,thereby ensuring the stability of the species over time.

(N/A)

Asexual reproduction	Sexual reproduction
$(a)$ Involves only one parent.	$(i)$ Involves two parents of opposite sex.
$(b)$ Gametes are not produced.	$(ii)$ Gametes are produced.
$(c)$ No fertilization and zygote formation occurs.	$(iii)$ Fertilization and zygote formation are observed.
$(d)$ Meiosis does not occur.	$(iv)$ Meiosis occurs during gamete formation.

During sexual reproduction,two types of gametes fuse. Although the gametes contain the same number of chromosomes,their $DNA$ is not identical due to the process of recombination during meiosis. This genetic shuffling generates variations among the offspring.

(N/A) Organisms require energy for survival,which they obtain through life processes such as nutrition and respiration.
$(b)$ Reproduction is an energy-intensive process that does not contribute to the survival of the individual organism.
$(c)$ The primary purpose of reproduction is the transfer of genetic material from one generation to the next through $DNA$ copying.
$(d)$ $DNA$ copying occurs with high fidelity but also introduces variations,which provide advantages to the species,ensuring its stability and survival in a changing environment.

(C) Reproduction is the biological process by which an organism produces new individual organisms (offspring). It is essential for the survival of a species and directly contributes to the growth and maintenance of a population over time.

(N/A) Germination: It is the process by which an embryo develops into a seedling under favorable conditions. It marks the beginning of the growth of a new plant from a seed.
Fertilization: It is the process of fusion of the male gamete (pollen grain/sperm) with the female gamete (ovum/egg cell) to form a zygote. It is a crucial step in sexual reproduction.

(N/A) $Planaria$ exhibits high regenerative capacity; therefore,each cut piece grows into a complete new organism.
$(b)$ The buds present in the notches of the $Bryophyllum$ leaf develop into new plantlets when they come in contact with moist soil.
$(c)$ The release of testosterone triggers the development of secondary sexual characteristics in boys during puberty,such as voice change,growth of facial hair,and increased muscle mass.

(N/A) The characteristics of sexual reproduction are as follows:
$1$. Two parents of opposite sex are involved in the process.
$2$. Two dissimilar gametes (male and female) are formed; the process of gamete formation involves meiosis.
$3$. Genetic variations are produced due to the recombination of genetic material.
$4$. It occurs in most higher organisms and some lower organisms.
$5$. Fertilization,which is the fusion of male and female gametes,leads to the formation of a diploid zygote.
$6$. It is a relatively slow and complex process compared to asexual reproduction.

(N/A)

$(a)$ Placenta	Uterus
The embryo receives nutrition from the mother's blood through a special tissue called the placenta.	The uterus is the organ where the embryo attaches and develops after fertilization.
$(b)$ Unisexual flowers	Bisexual flowers
Flowers that contain either stamens or carpels,but not both.	Flowers that contain both stamens and carpels.
$(c)$ Fertilization	Germination
The fusion of a male gamete with a female gamete to form a zygote.	The process by which an embryo in a seed grows into a seedling under suitable conditions.

(N/A)

Sexual Reproduction	Asexual Reproduction
$(i)$ Involves two parents - male and female.	$(i)$ Involves only one parent.
$(ii)$ Gametes are formed in both males (sperms) and females (ova).	$(ii)$ No gametes are produced.
$(iii)$ Fertilization and zygote formation occur.	$(iii)$ No fertilization or zygote formation occurs.
$(iv)$ Meiosis occurs during gamete formation.	$(iv)$ Meiosis does not occur at any stage of reproduction.
$(v)$ Genetic variation occurs in offspring.	$(v)$ Genetic variation does not occur; offspring are clones.

(N/A) $(i)$ Formation of sperms and changes in physical appearance occur.
$(ii)$ Thick hair growth on the face and voice begin to crack (deepen).
$(b)$ $A$ pollen tube grows out of the pollen grain and travels through the style to reach the ovary for fertilization.
$(c)$ $A$ zygote is formed,which is the process of fertilization.
$(d)$ Each piece grows into a complete new organism through the process of regeneration.
$(e)$ Buds may fall on the soil and develop into new independent plants.

(N/A) The fusion of a male gamete with a female gamete is known as fertilization.
$(b)$ The cycle that occurs every month when an egg is not fertilized is known as menstruation. It lasts for about $2$ to $8$ days,during which the lining of the uterus slowly breaks down and is discharged through the vagina as blood and mucus.
$(c)$ The splitting of a parent cell into two daughter cells,which can occur in any plane,is known as binary fission. It is observed in organisms like $Amoeba$.
$(d)$ When a vegetative part of a plant,such as the root,stem,or leaves,develops into a new plant under appropriate conditions,it is known as vegetative propagation.
$(e)$ When the body of an organism is cut into any number of pieces and each piece grows into a complete organism,this is known as regeneration. It is observed in $Hydra$ and $Planaria$.

(N/A) The style is the elongated,slender stalk that connects the stigma to the ovary in a flower. The pollen tube is a tubular structure that emerges from the pollen grain after pollination and grows through the style to deliver male gametes to the ovary.
$(b)$ In Hydra,a bud is a small outgrowth formed by repeated mitotic cell divisions at a specific site on the parent body,which eventually detaches to form a new individual. In Bryophyllum,buds are adventitious buds that develop in the notches along the leaf margins; when these leaves fall on moist soil,the buds develop into new independent plants.

(N/A) Reproduction is a biological process by which living organisms produce new individuals of the same species.
Organisms occupy specific places in the ecosystem,known as niches,by utilizing their ability to reproduce.
Reproduction involves $DNA$ copying,which acts as the source of information for synthesizing proteins,thereby determining and controlling the body design of the organism.
These specific body designs enable organisms to efficiently utilize a particular niche,which ensures the stability of the population of that species.
Furthermore,minor variations that occur during $DNA$ replication may also contribute to the long-term survival and stability of the species in changing environments.

(N/A)

Pollen tube	Style
It is the structure formed when pollen lands on a suitable stigma. It grows out of the pollen grain and travels through the style to reach the ovary.	It is the middle elongated part of the carpel which provides a path for the pollen tube to reach the ovary after pollination.

$(b)$

Fission in Amoeba	Fission in Plasmodium
$(i)$ It shows binary fission.	$(i)$ It shows multiple fission.
$(ii)$ The parent cell divides into two small,nearly identical daughter cells.	$(ii)$ The parent cell divides into several small,nearly equal-sized daughter individuals.

$(c)$

Fragmentation	Regeneration
It is a mode of asexual reproduction where the parent body splits into two or more fragments,and each fragment develops into an organism under favourable conditions,e.g.,$Spirogyra$.	It is the ability to regrow lost body parts; it is used as a mode of reproduction in some organisms like $Hydra$ and $Planaria$.

$(d)$

Bud of Hydra	Bud of Bryophyllum
It is an outgrowth formed on the body by regenerative cells. These buds develop into tiny individuals and detach from the parent body to become independent.	In $Bryophyllum$,buds are produced in the notches along the leaf margin. These buds fall on the soil and develop into new plants.

$(e)$

Vegetative propagation	Spore formation
It is a mode of asexual reproduction in which parts like the root,stem,and leaves develop into new plants under appropriate conditions.	It is a mode of asexual reproduction commonly seen in organisms like fungi. They reproduce through spores,which are minute,single-celled structures protected by thick walls until they find a moist surface to grow.

(N/A) $(i)$ Homologous organs are those which have the same basic structural design and developmental origin but perform different functions. Analogous organs are those which have different structural origins but perform similar functions.
$(ii)$ Pollination is the process of transfer of pollen grains from the anther to the stigma of a flower. Fertilisation is the process of fusion of the male gamete with the female gamete to form a zygote.
$(b)$ Fossils provide direct evidence for evolution. They help in establishing evolutionary relationships between organisms,show the sequence of evolutionary changes over time,and act as connecting links between different groups of organisms.

(A) Reproduction is a biological process by which living organisms produce new individuals similar to themselves.
It is not essential for the survival of an individual organism,unlike processes such as respiration,nutrition,or excretion.
However,it is essential for the survival of a species as it ensures the continuity of the species from one generation to the next.
Therefore,the primary purpose of reproduction is to continue the species generation after generation.

(D) Reproduction is a biological process by which living organisms produce new individuals similar to themselves.
Unlike nutrition,respiration,or excretion,reproduction is not necessary for the survival of an individual organism.
However,it is essential for the survival of a species as it ensures the continuity of life by passing on genetic information to the next generation,thereby preventing the extinction of the species.

(B) The biological process by which an organism produces new individuals of the same species is known as reproduction.
Growth refers to an increase in size or cell number,while fertilization is the fusion of gametes.
Spore formation is a specific method of asexual reproduction,but the general phenomenon of producing offspring is called reproduction.