Mix Examples -Reproduction in Organisms Questions in English

(D) Sexual reproduction is characterized by the fusion of male and female gametes,the formation of zygote,embryogenesis and variations. These events are grouped into three distinct stages:
$1$. Pre-fertilisation events: These include all the events prior to the fusion of gametes,specifically gametogenesis (formation of gametes) and gamete transfer.
$2$. Fertilisation: This is the actual process of the fusion of male and female gametes to form a diploid zygote.
$3$. Post-fertilisation events: These include events that occur after the formation of the zygote,such as the development of the zygote and embryogenesis.
Therefore,the correct sequential order is Pre-fertilisation $\rightarrow$ Fertilisation $\rightarrow$ Post-fertilisation,which corresponds to $I \rightarrow II \rightarrow III$.

(D) clone is defined as a group of individuals that are morphologically and genetically identical to each other and to their parent.
These individuals are produced through asexual reproduction,where no genetic recombination occurs.
Therefore,clones exhibit similarity in both their physical appearance (morphology) and their genetic makeup (genotype).

(D) The most essential event in sexual reproduction is fertilization. $ (a) $ Fertilization is defined as the fusion of male and female gametes to form a diploid zygote. Since $ (a) $ and $ (b) $ refer to the same biological process,both are correct.

(A) The time period from birth till natural death is called the life span of an organism.
The life span is generally divided into four stages:
$(i)$ Juvenility: The period of life span from birth until the organism develops the capacity to reproduce.
$(ii)$ Maturity: The stage where reproduction begins and flourishes.
$(iii)$ Senescence or ageing: The progressive deterioration of the body is called ageing,which ends in senescence.
$(iv)$ Death: The cessation of all vital activities of an organism at the end of senescence leads to death.

(D) Asexual reproduction is a common mode of reproduction in organisms that have a relatively simple organization.
It is the primary method of reproduction in single-celled organisms (like Monera and Protista).
It is also observed in plants and animals with simple body organization (e.g.,algae,fungi,and simple invertebrates like sponges or hydra).
In asexual reproduction,mitotic cell division occurs,which is faster and less complex than meiosis,allowing for rapid population growth.
Therefore,all the given options represent groups where asexual reproduction is common.

(A) True. Organisms that possess both male and female reproductive organs are known as hermaphrodites or bisexual organisms.
Examples include earthworms,sponges,tapeworms,and leeches.

(C) Morphologically and genetically similar organisms are called clones.
These are produced through asexual reproduction,which is a type of reproduction involving only a single organism.

(A) Gametes are always haploid $(n)$ regardless of whether the parent body is haploid $(n)$ or diploid $(2n)$.
If the parent body is haploid,it produces gametes through mitosis,where the chromosome number remains the same $(n \rightarrow n)$.
If the parent body is diploid,it produces gametes through meiosis,where the chromosome number is reduced to half $(2n \rightarrow n)$.

(C) Syngamy (fertilization) is the fusion of male and female gametes. It is classified into two types:
$(i)$ External Fertilization: When syngamy takes place in the external medium. Generally,the external medium is water,e.g.,amphibians and fishes.
(ii) Internal Fertilization: When syngamy takes place inside the female body,e.g.,reptiles,birds,and mammals.
Since syngamy can occur in both external and internal media,the correct answer is both $(a)$ and $(b)$.

(C) $Statement \; I$: Incorrect. Lower groups of organisms typically possess simple body designs.
$Statement \; II$: Correct. Asexual reproduction is the primary mode of reproduction in simpler, early-evolving organisms.
$Statement \; III$: Incorrect. Sexual reproduction is the dominant mode of reproduction in higher, more complex organisms.
$Statement \; IV$: Correct. Complex organisms that evolved later, such as angiosperms and vertebrates, predominantly utilize sexual reproduction, which is a more elaborate process compared to asexual reproduction.
Therefore, statements $II$ and $IV$ support the view that sexual reproduction appeared later in evolution.

(A) large number of offspring are produced in the case of external fertilization. This is because,in an external medium,the gametes and the developing embryos are exposed to various environmental hazards,predators,and unfavorable conditions. To ensure that at least some offspring survive to adulthood,organisms produce a vast number of gametes and offspring.

(B) The life span of an organism is the period from birth to the natural death of that organism.
According to biological data, the average life span of a cow is approximately $20-25\, years$.
The average life span of a horse is approximately $25-30\, years$.
Therefore, the correct option is $B$.

(A) Asexual reproduction involves the production of offspring from a single parent without the involvement of gamete formation or fusion (syngamy) and meiosis.
Since there is no recombination of genetic material, the offspring are genetically identical to the parent, forming clones.
Therefore, a plant can be multiplied indefinitely without any genetic variation.
Both statements are true, and $Statement\; 2$ explains why the plant remains unchanged (lack of meiosis/syngamy prevents variation).

(D) The average lifespan of the organisms listed is as follows:
$(A)$ Butterfly: $1-2 \text{ weeks}$ $(A-4)$
$(B)$ Crow: $15 \text{ years}$ $(B-3)$
$(C)$ Parrot: $140 \text{ years}$ $(C-2)$
$(D)$ Crocodile: $60 \text{ years}$ $(D-1)$
Therefore,the correct matching is $A-4, B-3, C-2, D-1$.

(B) The approximate life spans of the given organisms are as follows:
$1$. Elephant: $60-90 \text{ years}$ $(A-d)$
$2$. Fruit fly: $30 \text{ days}$ or $1 \text{ month}$ $(B-a)$
$3$. Rice plant: $3-4 \text{ months}$ $(C-b)$
$4$. Butterfly: $1-2 \text{ weeks}$ or $7-15 \text{ days}$ $(D-c)$
Therefore,the correct matching is $A-d, B-a, C-b, D-c$.

(D) Reproduction is a fundamental biological process that ensures the continuity of species. The method of reproduction adopted by an organism is not random but is influenced by several complex factors.
$1$. Habitat: The environment in which an organism lives (e.g.,aquatic vs. terrestrial) dictates the survival strategies and reproductive modes.
$2$. Internal physiology: The metabolic and hormonal state of the organism plays a crucial role in determining whether it reproduces sexually or asexually.
$3$. Genitalia: The presence and complexity of reproductive organs are essential for sexual reproduction.
Since all these factors collectively influence how an organism reproduces,the correct answer is $D$.

(D) Parthenogenesis is a form of asexual reproduction where an embryo develops from an unfertilized egg cell.
This phenomenon is observed in various organisms across the animal kingdom.
$1$. In $Rotifers$,parthenogenesis is a common mode of reproduction.
$2$. In $Turkey$ $birds$,parthenogenesis can occur,leading to the development of embryos from unfertilized eggs.
$3$. In $Some$ $reptiles$ (such as certain species of lizards),parthenogenesis is also a known reproductive strategy.
Since all the given options exhibit this process,the correct answer is $D$.

(A) The oestrus cycle refers to the cyclic changes in the activities of ovaries and accessory ducts in non-primate mammals.
These changes occur specifically during the reproductive or seasonal period of the organism.
Therefore,it is a characteristic feature of seasonal breeders.

(D) represents a female cockroach because the presence of the brood pouch and specific abdominal structures are distinguishing characteristics of the female.
$B$ represents $Marchantia$, a liverwort with a thalloid body where male and female sex organs are borne on separate thalli (dioecious).
$C$ represents a bisexual flower because it contains both male (stamen) and female (pistil) reproductive parts within the same flower.

(C) Figure $A$ shows isogametes (or homogametes),where both gametes are morphologically identical.
Figure $B$ shows heterogametes,where there is a significant size difference between the two gametes.
Figure $C$ shows distinct heterogametes,specifically an egg (ovum) and a sperm,which are morphologically and physiologically different.

(A) The presence of a diploid zygote is universal in all sexually reproducing organisms.
This is true regardless of whether the parents are haploid or diploid.
In organisms with a haploid parent body,the diploid zygote undergoes meiosis to produce haploid spores,which develop into a haploid body.
In diploid organisms,the diploid zygote undergoes mitosis to develop into a diploid individual.

(A) The average life spans of the given organisms are as follows:
$1$. Fruit fly: Approximately $2$ weeks.
$2$. Rice: Approximately $3-4$ months.
$3$. Rose: Approximately $5-7$ years.
Therefore,the order of increasing life span is: Fruit fly < Rice < Rose.

(D) The method of reproduction in an organism is influenced by several complex factors:
- $1$. Organism's habitat: The availability of resources and environmental stability in a habitat significantly influences the reproductive strategy. For example,organisms in nutrient-deficient or stressful conditions often switch to sexual reproduction to increase genetic diversity.
- $2$. Environmental factors: External conditions such as temperature,light,and water availability act as cues that trigger reproductive cycles in many species.
- $3$. Internal physiology: The hormonal balance,metabolic state,and genetic makeup of an organism determine its readiness and capacity to reproduce.
Since all these factors play a crucial role in determining the reproductive mode of an organism,the correct answer is $D$.

(D) Asexual reproduction is a mode of reproduction where a single parent produces offspring.
It is common in single-celled organisms (like bacteria and protists) and in organisms with simple body organization (like many algae and fungi).
Since both option $A$ and option $B$ are correct,the most appropriate answer is $D$.

(D) Unicellular organisms like bacteria and amoeba are considered immortal because they do not undergo natural death. During reproduction,the parent cell divides into two daughter cells through binary fission,meaning the original parent organism continues to exist as part of the offspring. Thus,there is no natural death for these organisms.

(D) In unicellular organisms,cell division is synonymous with reproduction.
$Amoeba$ and $Bacteria$ are unicellular organisms that reproduce by binary fission,which is a form of cell division.

(D) In yeast,budding is a form of asexual reproduction.
$1$. Cytokinesis is unequal,as a small bud is formed on the parent cell while the parent remains intact.
$2$. Since it is asexual reproduction,the offspring are genetically identical to the parent,meaning clones are produced.
$3$. The identity of the parent is not lost.
Therefore,both $A$ and $C$ are correct,making $D$ the right choice.

(C) The organism shown in the image is $Eichhornia$ $crassipes$ (Water Hyacinth).
It is known as the 'Scourge of the water bodies' because it grows rapidly and covers the entire surface of the water.
It reproduces vegetatively through structures called offsets.
It causes a significant reduction in dissolved oxygen levels in the water,leading to the death of fishes and other aquatic organisms.
It is typically found in stagnant or standing water,not in running water. Therefore,the statement 'Found in running water' is incorrect.

(D) Vegetative reproduction is considered a form of asexual reproduction because:
$1$. It involves only a single parent (uniparental).
$2$. There is no formation or fusion of gametes.
$3$. It involves only mitotic cell division, meaning meiosis does not occur.
Since all three statements ($A$, $B$, and $C$) are correct, the correct choice is $D$.

(A) The events involved in all sexually reproducing organisms are the same and occur in a sequential manner.
The sequence of events is: $Pre-fertilization \rightarrow Fertilization \rightarrow Post-fertilization$.

(D) In biology,sexuality refers to whether an organism is monoecious (bisexual) or dioecious (unisexual).
$1$. Coconut,Cucurbits,and Chara are examples of monoecious plants,meaning both male and female reproductive organs are present on the same individual.
$2$. Papaya is a dioecious plant,meaning male and female reproductive organs are present on separate individuals (unisexual).
Therefore,Papaya is the odd one out.

(A) In an onion $(Allium \text{ cepa})$, the diploid number of chromosomes $(2n)$ is $32$.
Meiocytes are diploid cells that undergo meiosis to produce gametes.
Therefore, the number of chromosomes in the meiocyte is $2n = 32$.
The gametes are haploid cells produced after meiosis, containing half the number of chromosomes $(n)$.
Thus, the number of chromosomes in the gamete is $n = 16$.
So, the number of chromosomes in the meiocyte and gamete of an onion is $32$ and $16$, respectively.

(C) In fungi,the term $homothallic$ refers to a condition where both male and female reproductive structures are present on the same thallus or mycelium. This is equivalent to a $bisexual$ or $monoecious$ condition,where a single organism can produce both types of gametes.

(B) In the provided figure,$A$ represents isogametes of the alga Cladophora,which are morphologically similar.
$B$ represents heterogametes (antherozoid and egg) of the brown alga Fucus,which are morphologically distinct.
Therefore,the correct representation is Isogametes of Cladophora and Heterogametes of Fucus.

(B) The structures involved in asexual reproduction are: Zoospore,Conidia,Tuber,and Offset.
Structures not associated with asexual reproduction are: Pollen and Zygote.
$1$. Pollen is a male gametophyte involved in sexual reproduction.
$2$. Zygote is a diploid cell formed by the fusion of male and female gametes during sexual reproduction.
Therefore,there are $2$ structures that are not associated with asexual reproduction.

(C) In organisms with simple organization (like algae and fungi), the following observations are made:
$(a)$ Asexual reproduction typically occurs under favourable conditions, while sexual reproduction is often triggered by unfavourable conditions to ensure survival through genetic recombination.
$(b)$ Asexual reproduction is more frequent as it is a rapid process, whereas sexual reproduction is less frequent.
$(c)$ Asexual reproduction involves the formation of spores (e.g., zoospores), while sexual reproduction involves the formation and fusion of gametes.
$(d)$ Asexual reproduction involves mitosis (or simple fission), while sexual reproduction involves meiosis to produce haploid gametes.
Therefore, statements $(a)$, $(b)$, and $(c)$ are correct. Statement $(d)$ is incorrect because the types of cell division are swapped.

(C) In annual and biennial plants,there is a clear-cut vegetative,reproductive,and senescent phase. These plants complete their life cycle within one or two seasons,respectively,and then die. In contrast,many perennial species show complex,overlapping phases,making a clear-cut distinction difficult. Therefore,all annuals and biennials exhibit these distinct phases.

(A) In many algae and a few fungi,both male and female gametes are motile (flagellated). This condition is known as isogamy or anisogamy,where both gametes are morphologically similar or slightly different but both possess the ability to move.

(C) In organisms exhibiting internal fertilisation,the male gametes are produced in very large numbers to ensure that they reach the egg,as there is a significant risk of loss during the journey to the site of fertilisation.
Conversely,the number of female gametes produced is significantly reduced because the internal environment provides protection and increases the probability of successful fertilisation.
Therefore,there is a reduction in the number of female gametes and an increase in the number of male gametes.

(C) In many aquatic organisms,such as most algae,fishes,and amphibians,syngamy occurs in the external medium (water).
To enhance the chances of syngamy,these organisms exhibit great synchrony between the sexes and release a large number of gametes into the surrounding medium.
This is a characteristic feature of external fertilization.

(D) Statement $I$ is incorrect because the life span of an organism is not necessarily correlated with its size (e.g.,a crow and a parrot have similar sizes but vastly different life spans).
Statement $II$ is correct because death is an inevitable biological reality for all individual organisms.
Statement $III$ is correct because an organism's reproductive strategy is influenced by its habitat,internal physiology,and other environmental factors.
Statement $IV$ is correct because asexual reproduction involves a single parent and does not necessarily require the formation or fusion of gametes.
Therefore,statements $II, III,$ and $IV$ are correct. However,based on the provided options,the most appropriate choice is $D$ ($II, IV$ are correct).

(D) In the given figures:
$a$ represents the Nucule (female sex organ in Chara).
$b$ represents the Globule (male sex organ in Chara).
$c$ represents the Stamen (male sex organ in a flower).
$d$ represents the Carpel/Pistil (female sex organ in a flower).
$e$ represents the Archegoniophore (female sex organ bearer in Marchantia).
$f$ represents the Antheridiophore (male sex organ bearer in Marchantia).
Therefore,the female sex organs are $a$ (Nucule),$d$ (Carpel),and $e$ (Archegoniophore). The correct option is $D$.

(C) Statement $I$ is correct: Asexual reproduction is indeed common in single-celled organisms and those with simple body organization.
Statement $II$ is incorrect: Conidia,buds,and gemmules are asexual reproductive structures,not sexual structures.
Statement $III$ is correct: Runner,rhizome,sucker,tuber,offset,and bulb are all examples of vegetative propagules in plants.
Statement $IV$ is incorrect: The invasive weed found growing in freshwater bodies is $Eichhornia$ $crassipes$ (water hyacinth),not $Zostera$. $Zostera$ is a marine angiosperm (sea grass).
Therefore,statements $I$ and $III$ are correct.

(C) $I$. Annual and biennial plants exhibit distinct vegetative,reproductive,and senescent phases,making this statement correct.
$II$. Bamboo species are well-known for flowering only once in their lifetime,typically after a period of $50-100$ years,making this statement correct.
$III$. $Strobilanthus$ $kunthiana$ (Neelakuranji) is a monocarpic plant,but it flowers once every $12$ years,not $6$ years. Therefore,this statement is incorrect.
Thus,statements $I$ and $II$ are correct.

(C) The Assertion $(A)$ is correct because the juvenile phase (or vegetative phase in plants) is the period of growth and development before an organism reaches reproductive maturity. Once this phase ends,the organism gains the ability to reproduce.
The Reason $(R)$ is incorrect. The time period between the first and next flowering in plants is not the definition of juvenility. Juvenility refers to the period from birth/germination to the onset of reproductive maturity. The period between two flowering events is often referred to as the inter-flowering period in polycarpic plants.

(A) Reproduction is defined as a biological process in which an organism gives rise to young ones (offspring) similar to itself.
This process is essential for the survival of species as it increases the population size and ensures the continuity of the species from generation to generation.
Therefore,both the Assertion and the Reason are correct,and the Reason provides a valid explanation for why reproduction is a necessary biological process.

(D) Assertion $A$ states that endogamy is common in the majority of animals,which is incorrect. Endogamy refers to breeding within a closed group or population,whereas most animals exhibit exogamy or cross-breeding to promote genetic diversity.
Reason $R$ states that fusing gametes are quite different and develop from different individuals. This is a characteristic of sexual reproduction (specifically cross-fertilization),which is generally true for many animals,but it does not support the assertion because the assertion itself is false.
Since the assertion is false and the reason describes a process contrary to endogamy,both statements are considered incorrect in the context of the assertion provided.
Therefore,the correct option is $D$.

(B) Monocarpic plants are those that flower and produce seeds only once in their lifetime,after which they die. Cereals like wheat,rice,and maize are annual plants that complete their life cycle in one season,flower once,and then die,making them monocarpic.
All sexually reproducing organisms,including monocarpic plants,exhibit distinct phases in their life cycle: the juvenile phase (growth),the reproductive phase (flowering/fruiting),and the senescent phase (aging/death).
Therefore,both statements are correct,and the presence of these distinct phases is a general characteristic of all organisms,but the specific reason for being monocarpic is the single flowering event,not just the existence of these phases. Thus,$B$ is the correct choice.

(B) The Assertion is correct because in all sexually reproducing organisms,the fusion of male and female gametes results in the formation of a diploid zygote,which serves as the vital link between two generations.
The Reason is also correct because embryogenesis involves the development of an embryo from the zygote through the processes of cell division (mitosis) and cell differentiation (specialization of cells into tissues and organs).
However,the Reason does not explain why the zygote is the first cell of the new generation; it merely describes the processes that occur after the zygote is formed. Therefore,both are correct,but the Reason is not the correct explanation of the Assertion.

(C) The Assertion is correct because,in single-celled organisms like bacteria or protozoa,the parent cell divides into two daughter cells,effectively continuing its life without a natural death. Thus,they are considered biologically immortal.
The Reason is incorrect because budding is a form of asexual reproduction found in organisms like yeast or Hydra,but it does not make multicellular plant or animal species 'immortal'. Multicellular organisms have a defined life span and undergo senescence and death. Therefore,the statement that they do not die because of budding is factually wrong.