Mix Examples - How do Organisms Reproduce? Questions in English

(A) Asexual reproduction is a mode of reproduction in which a single parent produces offspring without the involvement of gamete fusion.
$(i)$ Banana reproduces vegetatively (a form of asexual reproduction).
$(ii)$ Dog reproduces sexually.
$(iii)$ Yeast reproduces asexually by budding.
$(iv)$ Amoeba reproduces asexually by binary fission.
Therefore,organisms $(i), (iii),$ and $(iv)$ reproduce by the asexual method.

(B) In a flowering plant, the reproductive parts are located within the flower.
- The male reproductive part is the $stamen$, which consists of an $anther$ and a $filament$. The $anther$ produces pollen grains, which contain the male gametes.
- The female reproductive part is the $pistil$ (or $carpel$), which consists of the $stigma$, $style$, and $ovary$. The $ovary$ contains ovules, which produce the female gametes (egg cells).
- Therefore, the $anther$ produces male gametes and the $ovary$ produces female gametes.

(C) The process of sexual reproduction in a flower follows a specific biological order:
$1$. $Pollination$: The transfer of pollen grains from the anther to the stigma of a flower.
$2$. $Fertilisation$: The fusion of the male gamete with the female gamete (egg) to form a zygote.
$3$. $Embryo$: The zygote develops into an embryo within the seed.
$4$. $Seedling$: Upon germination, the seed develops into a new plant or seedling.
Therefore, the correct sequence is $Pollination \rightarrow Fertilisation \rightarrow Embryo \rightarrow Seedling$.

(D) Asexual reproduction involves only a single parent $(i)$.
Since there is only one parent,there is no fusion of gametes $(ii)$,which prevents the mixing of genetic material from two different sources.
As a result,the offspring produced are genetically identical to the parent and to each other,often referred to as clones.
Statements $(iii)$ and $(iv)$ are irrelevant to the genetic similarity of the offspring.
Therefore,the correct combination is $(i)$ and $(ii)$.

(A) The characters or traits are passed from parents to offspring through the process of inheritance.
These traits are controlled by specific segments of $DNA$ known as $genes$.
$Genes$ are located on chromosomes within the nucleus of the cell.
During reproduction, these $genes$ are inherited by the offspring, which determines their physical and biological characteristics.

(B) During reproduction,$DNA$ is copied and passed from parents to offspring.
This process ensures that the offspring inherit the basic body design and fundamental characteristics of the parents,leading to similarities.
However,the process of $DNA$ copying is not perfectly accurate and involves small errors,which leads to variations in the offspring.
Therefore,offspring exhibit both similarities and variations when compared to their parents.

(C) $Amoeba$ reproduces by binary fission,$Spirogyra$ reproduces by fragmentation,and $Yeast$ reproduces by budding. All these methods are types of asexual reproduction. Therefore,the common feature among these organisms is that they all reproduce asexually.

(A) $Spirogyra$ is a filamentous green alga. When it matures,its body breaks into smaller pieces or fragments. Each fragment grows into a new individual. This method of asexual reproduction is known as fragmentation.

(A) In $Plasmodium$,the organism reproduces by a process known as multiple fission.
During this process,the parent cell divides into many daughter cells simultaneously.
This is an asexual mode of reproduction where the nucleus divides repeatedly,followed by the division of the cytoplasm,resulting in the formation of numerous daughter individuals.

(B) In flowering plants, the reproductive process follows a specific sequence:
$1$. Gametes: The process begins with the formation of male and female gametes (pollen grains and egg cells).
$2$. Zygote: Fertilization occurs when the male and female gametes fuse to form a single-celled $zygote$.
$3$. Embryo: The $zygote$ undergoes repeated cell divisions to develop into an $embryo$ within the seed.
$4$. Seedling: Upon germination, the $embryo$ grows into a young plant known as a $seedling$.
Therefore, the correct sequence is: $gametes \rightarrow zygote \rightarrow embryo \rightarrow seedling$.

(C) In sexually reproducing organisms,the process of meiosis occurs during gamete formation.
Meiosis is a reductional division that reduces the chromosome number to half $(n)$ in the gametes compared to the parent cell $(2n)$.
When the male gamete $(n)$ and female gamete $(n)$ fuse during fertilization,the diploid chromosome number $(2n)$ is restored in the zygote.
This ensures that the chromosome number remains constant across generations in a particular species.

(D) $Rhizopus$ is a common bread mold that reproduces through spore formation.
It consists of a network of fine,thread-like,tubular structures known as $hyphae$.
Some of these $hyphae$ grow vertically and develop swollen,knob-like structures at their tips called $sporangia$.
These $sporangia$ contain spores which,upon release,germinate to form new individuals.

(A) Vegetative propagation is a type of asexual reproduction in plants where new individuals are formed from vegetative parts of the parent plant.
These vegetative parts include the stem,roots,and leaves.
Flowers,fruits,and seeds are involved in sexual reproduction,not vegetative propagation.
Therefore,the correct option is $A$.

(B) Bread mould (Rhizopus) reproduces through spore formation.
$(i)$ The production of a large number of spores allows the fungus to disperse widely and increase the probability of landing on a suitable substrate.
$(ii)$ Bread provides an ideal environment for the growth of mould because it contains moisture and nutrients (carbohydrates) necessary for the fungus to thrive.
$(iii)$ and $(iv)$ are structural characteristics of the fungus,but they are not the primary factors responsible for the 'rapid spread' across the bread surface compared to the reproductive strategy (spores) and environmental conditions (moisture/nutrients).
Therefore,the correct factors are $(i)$ and $(ii)$.

(C) The pollen tube is a tubular structure produced by the male gametophyte (pollen grain) after it lands on the stigma of a flower.
Its primary function is to transport the male gametes from the pollen grain to the ovule located within the ovary.
Therefore,the growth of the pollen tube must continue until it reaches the ovule.
Consequently,the total length of the pollen tube is determined by the distance it must travel from the point of germination (the upper surface of the stigma) to the target (the ovule).

(D) Statement $(i)$ is false because flowers can be unisexual (staminate or pistillate) or bisexual.
Statement $(ii)$ is true because flowers are the reproductive structures in angiosperms.
Statement $(iii)$ is false because flowers are only produced by angiosperms (flowering plants),not by all plant groups like algae,bryophytes,or pteridophytes.
Statement $(iv)$ is true because after fertilisation,the ovary develops into a fruit and the ovules develop into seeds.
Therefore,statements $(ii)$ and $(iv)$ are correct.

(A) Unisexual flowers are those that contain either only stamens (male reproductive part) or only pistils (female reproductive part),but not both.
Statement $(i)$ is false because unisexual flowers do not possess both stamen and pistil.
Statement $(ii)$ is true as they contain either stamen or pistil.
Statement $(iii)$ is true because unisexual flowers often require cross-pollination to transfer pollen from the male flower to the female flower.
Statement $(iv)$ is true because fruits are formed from the ovary of the pistil. Flowers possessing only stamens (staminate flowers) lack an ovary and therefore cannot produce fruits.
Thus,statements $(ii), (iii),$ and $(iv)$ are correct.

(B) Sexual reproduction in flowering plants involves the fusion of male and female gametes,making statement $(i)$ true.
Fertilisation,which is the fusion of these gametes,is a compulsory event in sexual reproduction,making statement $(ii)$ true.
The product of the fusion of male and female gametes is a zygote,making statement $(iii)$ true.
Offspring produced through sexual reproduction are genetically different from their parents due to meiosis and recombination,meaning they are not clones. Clones are produced through asexual reproduction. Thus,statement $(iv)$ is false.
Therefore,statements $(i), (ii),$ and $(iii)$ are correct.

(C) The provided figure shows the internal structure of a germinating seed.
$A$ represents the plumule,which is the part of the embryo that develops into the shoot system.
$B$ represents the cotyledon,which is the seed leaf that provides nourishment to the developing embryo.
$C$ represents the radicle,which is the part of the embryo that develops into the root system.
Therefore,the parts $A, B$,and $C$ are sequentially plumule,cotyledon,and radicle.

(D) Sexual reproduction involves the fusion of male and female gametes,which are produced by two parents of the same species.
During the formation of gametes,the process of meiosis occurs,which includes recombination and crossing over of genetic material.
This results in new combinations of genes in the offspring,leading to genetic variation.
Since the genetic material is contributed by two different individuals of the same species,the offspring possess a unique combination of traits,which is different from both parents.

(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.

(B) During adolescence,the human body undergoes significant physical and hormonal changes.
Sexual maturation in boys is characterized by specific secondary sexual characteristics.
$A$. Loss of milk teeth occurs during childhood,not adolescence.
$B$. Cracking of voice (deepening of the voice) is a primary secondary sexual characteristic in boys caused by the enlargement of the larynx under the influence of testosterone.
$C$. Increase in height occurs in both boys and girls during adolescence,but it is a general growth spurt rather than a specific sign of sexual maturation.
$D$. Weight gain is a general physiological change associated with overall growth and development,not specifically sexual maturation.
Therefore,the correct option is $B$.

(C) In human females,the onset of the reproductive phase is marked by the beginning of the menstrual cycle,which is known as menarche.
This process involves the periodic shedding of the uterine lining and is a clear indicator that the female reproductive system has become functional.
While body growth,changes in hair pattern,and voice changes are secondary sexual characteristics that occur during puberty,they do not specifically mark the onset of the reproductive phase as clearly as the first menstruation.

(D) In human males,the testes are located outside the abdominal cavity in a pouch-like structure called the scrotum.
This is because the process of spermatogenesis (formation of sperm) requires a temperature that is $2-2.5^{\circ}C$ lower than the normal body temperature.
The scrotum provides this cooler environment,which is essential for the healthy development and survival of sperm.

(A) The testes are the primary male reproductive organs. Their main functions at puberty include:
$1$. Formation of germ cells (spermatozoa),which is the process of spermatogenesis.
$2$. Secretion of the male sex hormone,testosterone,which is responsible for secondary sexual characteristics in males.
Conversely,the development of the placenta is a function associated with the female reproductive system during pregnancy,and the secretion of estrogen is primarily a function of the ovaries in females.
Therefore,$(iii)$ and $(iv)$ are not functions of the testes.

(B) In the male reproductive system,sperms are produced in the $Testis$.
From the $Testis$,sperms are transported through the $Vas$ $deferens$ (also known as the sperm duct).
The $Vas$ $deferens$ then joins the $Urethra$,which acts as a common passage for both urine and sperms.
Therefore,the correct sequence is $Testis \to Vas$ $deferens \to Urethra$.

(C) Sexually Transmitted Diseases $(STDs)$ are infections that are primarily spread through sexual contact.
$Syphilis$,$HIV-AIDS$,and $Gonorrhoea$ are well-known examples of $STDs$.
$Hepatitis$ (specifically $Hepatitis-B$) can be transmitted sexually,but the term '$Hepatitis$' generally refers to inflammation of the liver,which can be caused by various factors including viral infections (like $Hepatitis-A$,which is transmitted through contaminated food or water) or alcohol consumption.
Therefore,among the given options,$Hepatitis$ is the most appropriate answer as it is not exclusively or primarily classified as an $STD$ in the same category as the others.

(B) The process of removing stamens from a bisexual flower is known as emasculation.
If a flower produces fruit after the removal of its own stamens,it indicates that cross-pollination has occurred.
Cross-pollination is the transfer of pollen grains from the anther of one flower to the stigma of another flower of the same or a different plant.
Since the pistil (stigma,style,and ovary) remains intact,it is capable of receiving pollen grains from an external source (another flower).
Once the pollen grains land on the stigma,they germinate to form a pollen tube,which travels down the style to reach the ovary,resulting in fertilization and subsequent fruit formation.

(B) Yes,cell division can be considered a type of reproduction in unicellular organisms.
This is because,in unicellular organisms like bacteria or amoeba,cell division (such as binary fission) directly results in the formation of two or more daughter cells.
Since these daughter cells are independent individuals,the process of cell division effectively increases the population of the organism,which is the definition of reproduction.

(N/A) clone is defined as an individual organism that is genetically and morphologically identical to its parent.
Offspring formed by asexual reproduction exhibit remarkable similarity because they are produced from a single parent without the fusion of gametes.
Since asexual reproduction involves only mitotic cell division,the offspring receive exact copies of the parent's $DNA$,resulting in genetic uniformity.

(N/A) During sexual reproduction,the process of meiosis (reduction division) occurs during gamete formation. This process reduces the chromosome number to half in both male and female gametes. When these two haploid gametes fuse during the process of fertilization,the diploid number of chromosomes,which is identical to that of the parents,is restored in the zygote and subsequently in the offspring.

(N/A) Yeast is a heterotrophic organism that requires an external source of energy to perform metabolic activities,including reproduction.
Sugar solution provides the necessary carbohydrates (glucose/sucrose) that yeast cells break down through respiration to generate $ATP$ (energy).
In water,there is no source of nutrition or energy available for the yeast cells to sustain their life processes or to undergo cell division,hence they fail to multiply.

(N/A) Moisture is an essential factor for the growth of fungal hyphae. $A$ moist slice of bread provides both the necessary moisture and nutrients required for the bread mould to thrive. In contrast,a dry slice of bread provides nutrients but lacks the moisture needed for the spores to germinate and the hyphae to grow,thus preventing the mould from growing.

(N/A) Sexual reproduction involves two parents with different sets of characters.
$(b)$ The process of meiosis during gamete formation leads to genetic recombination,resulting in different gene combinations in gametes.

(N/A) Yes,a Planaria cut vertically into two halves can regenerate into two complete individuals. This is possible due to the presence of specialized cells that proliferate and make large numbers of cells,which then undergo changes to become various cell types and tissues. In the provided figures,the shaded parts in $D$ and $E$ represent the newly regenerated halves that have grown to replace the missing sections.

(N/A) No,there is no direct correlation between the size of an organism and its chromosome number. For example,some small organisms have more chromosomes than larger ones.
$(b)$ No,the process of reproduction follows a biological pattern specific to the species and is not dependent on the total number of chromosomes.
$(c)$ Yes,since chromosomes are primarily composed of $DNA$ and proteins,an increase in the number of chromosomes typically results in a higher total quantity of $DNA$ within the cell.

(N/A) In a tobacco plant,the male gamete is a haploid cell $(n)$ containing $24$ chromosomes.
Since the female gamete is also a haploid cell $(n)$,it will also contain $24$ chromosomes.
The zygote is formed by the fusion of the male and female gametes,making it a diploid cell $(2n)$.
Therefore,the number of chromosomes in the zygote is $24 + 24 = 48$.

(N/A) Fertilisation is the process of fusion of male and female gametes. In flowering plants,the male gametes are contained within the pollen grains. Pollination is the transfer of pollen grains from the anther to the stigma of a flower. If pollination does not occur,the male gametes cannot reach the female gametes present in the ovary. Therefore,without the presence of male gametes,fertilisation cannot take place.

(N/A) Yes,the chromosome number remains constant in the zygote,embryonal cells,and the adult of a particular organism.
This constancy is maintained because all these cells are formed through mitotic cell division.
In mitosis,the parent cell divides to produce two daughter cells that have the same number of chromosomes as the parent cell,ensuring genetic stability across these developmental stages.

(B) After fertilization,the male gamete fuses with the female gamete (egg cell) to form a zygote. This process occurs within the ovule. The ovule is located inside the ovary of the flower. Therefore,the zygote is located inside the ovule.

(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.

(D) General growth refers to the overall developmental processes in the body,such as an increase in height,weight gain,and changes in the shape and size of the body.
Sexual maturation is specific to the changes that occur during puberty,such as the cracking of the voice,the appearance of new hair patterns,and the development of breasts in females.
While general growth is a continuous process of physical development,sexual maturation marks the transition toward reproductive maturity.

(N/A) The path of sperm during ejaculation is as follows: $Testis \rightarrow Epididymis \rightarrow Vas \ deferens \rightarrow Urethra \rightarrow Penis$.
Associated glands and their functions:
$1$. $Seminal \ vesicles$: They secrete a fluid that provides nutrition to the sperms and makes their transport easier.
$2$. $Prostate \ gland$: It secretes a fluid that nourishes the sperms and helps in their motility.
$3$. $Bulbourethral \ glands$: They secrete a lubricating fluid that neutralizes the acidity of the urethra.

(B) If fertilisation does not occur,the egg dies and the thick,spongy lining of the uterus,which was prepared to nourish the embryo,is no longer needed. Consequently,this lining slowly breaks down and is discharged from the body through the vagina in the form of blood and mucus,a process known as menstruation.

(B) Following the implantation of the embryo,the uterine wall undergoes significant changes to support the developing fetus.
$1$. The uterine lining (endometrium) thickens and becomes highly vascularized,meaning it is richly supplied with blood to provide nourishment.
$2$. $A$ specialized tissue called the $placenta$ develops,which acts as a structural and functional connection between the embryo and the mother's uterine wall.
$3$. The $placenta$ facilitates the exchange of nutrients,oxygen,and waste products between the maternal blood and the fetal blood.

(C) Mechanical barriers,such as condoms,act as a physical shield that prevents sperm from reaching the egg,thereby effectively preventing pregnancy.
Additionally,these barriers provide a protective layer that prevents the transmission of sexually transmitted infections $(STIs)$ during sexual intercourse.

(N/A) Ovary: It is responsible for the production of the egg (ovum).
$(b)$ Oviduct (Fallopian tube): It is the site where fertilisation occurs.
$(c)$ Uterus: It is the site of implantation where the embryo develops.
$(d)$ Vagina: It serves as the passage for the entry of sperms into the female reproductive tract.

(A) The ratio of chromosome number between an egg (haploid,$n$) and its zygote (diploid,$2n$) is $1:2$.
Sperms are genetically different from eggs because sperms contain either an $X$ or a $Y$ chromosome,whereas an egg always contains an $X$ chromosome.

(N/A) Budding,fragmentation,and regeneration are considered asexual types of reproduction because they involve only a single parent and do not require the formation or fusion of gametes.
Regeneration in Planaria:
$1$. If a Planaria is accidentally cut into several pieces,each piece contains specialized cells that proliferate and make large numbers of cells.
$2$. From this mass of cells,different cell types undergo changes to become various cell types and tissues.
$3$. These changes take place in an organized sequence referred to as development.
$4$. Eventually,these pieces grow into complete new individuals.
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(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.