Mix Examples -Reproduction in Organisms Questions in English

(A) In bacteria,fungi,and lower plants,thick-walled structures called $A-$Spores are formed to survive $B-$Unfavourable conditions. These spores remain dormant until suitable environmental conditions return. In higher plants,$C-$Seeds and other vegetative propagules (like tubers,rhizomes,etc.) act as perennating structures that help the plant survive stress periods and aid in dispersal. When favourable moisture and temperature conditions are met,they germinate to produce new plants. Therefore,the correct sequence is $A-$Spores,$B-$Unfavourable,$C-$Seeds.

(N/A) Senescence phase: After the reproductive phase,hormonal changes gradually slow down the production of male and female gametes.
$\rightarrow$ This phase is known as the senescence phase or old age.
$\rightarrow$ It brings about concomitant changes in the body of the organism,such as the slowing down of metabolism.
$\rightarrow$ This is the final phase of the life span.
$\rightarrow$ Old age ultimately leads to death.

Meiocytes are specialized diploid $(2n)$ cells that undergo meiosis to produce haploid $(n)$ gametes.
In diploid organisms, such as pteridophytes, gymnosperms, angiosperms, and most animals, gametes are produced through the process of meiosis.
At the end of meiosis, only one set of chromosomes $(n)$ is incorporated into each gamete.
Table: Chromosome numbers in meiocytes $(2n)$ and gametes $(n)$ of some organisms.

Name of Organism	Chromosome Number in Meiocyte $(2n)$ / Gamete $(n)$
Human Beings	$46 / 23$
Housefly	$12 / 6$
Rat	$42 / 21$
Dog	$78 / 39$
Cat	$38 / 19$
Fruit fly	$8 / 4$
Ophioglossum (a fern)	$1260 / 630$
Apple	$34 / 17$
Rice	$24 / 12$
Maize	$20 / 10$
Potato	$48 / 24$
Butterfly	$380 / 190$
Onion	$32 / 16$

(N/A)

Oviparous	Viviparous
$(1)$ Fertilization usually takes place outside the body.	$(1)$ Fertilization takes place inside the body.
$(2)$ Fertilized eggs are covered by a hard calcareous shell.	$(2)$ Zygote develops into a young one within the body of the female.
$(3)$ After the completion of the incubation period,young ones hatch out.	$(3)$ After the completion of the gestation period,young ones are delivered out of the female body.

(A-D) The correct matches are as follows:
$(1)$ Binary fission: $(f)$ Amoeba and $(h)$ Paramoecium.
$(2)$ Budding: $(e)$ Yeast and $(g)$ Hydra.
$(3)$ Zoospore: $(d)$ Algae (e.g.,Chlamydomonas).
$(4)$ Conidia: $(a)$ Penicillium.
$(5)$ Tuber: $(c)$ Potato.
$(6)$ Leaf buds: $(b)$ Bryophyllum.
Therefore,the matching sequence is: $(1-f, h), (2-e, g), (3-d), (4-a), (5-c), (6-b)$.

(B) The correct matches are as follows:
$(1)$ Earthworm is a hermaphrodite (bisexual), meaning it contains both male and female reproductive organs in the same individual. Thus, $(1-b)$.
$(2)$ Cockroach is dioecious, meaning male and female reproductive organs are present in separate individuals. Thus, $(2-c)$.
$(3)$ Honey bee exhibits parthenogenesis, where unfertilized eggs develop into new individuals (drones). Thus, $(3-d)$.
$(4)$ Rotifers are organisms where males are often absent in certain populations, and reproduction occurs via parthenogenesis. Thus, $(4-a)$.
Therefore, the correct sequence is $(1-b, 2-c, 3-d, 4-a)$.

(A) $(1-g)$ Uniparental reproduction is a characteristic of asexual reproduction.
$(2-e)$ Budding is a common method of asexual reproduction in Hydra.
$(3-b)$ Gemmules are internal buds found in sponges like Spongilla.
$(4-i)$ Syngamy refers to the fusion of two haploid gametes to form a diploid zygote.
$(5-h)$ Fusion of similar gametes is known as isogamy.
$(6-a)$ Biparental reproduction is a characteristic of sexual reproduction.
$(7-c)$ Plasmodium is a haploid organism (in its vegetative stage).
$(8-f)$ Conidia are asexual reproductive structures found in Penicillium.
$(9-d)$ Multiple fission is a process where the parent cell divides into many daughter cells, often associated with the formation of gametes or spores in some contexts; however, in this specific matching set, it relates to the production of multiple units.

(D) The correct matches are as follows:
$P$. Fungi reproduce through asexual spores $(III)$.
$Q$. Yeast and Hydra reproduce through budding $(I)$.
$R$. Planaria exhibits true regeneration $(II)$.
$S$. Fungi, filamentous algae, and the protonema of mosses all multiply by fragmentation $(IV)$.
Therefore, the correct sequence is $(P-III), (Q-I), (R-II), (S-IV)$.

(B) The provided figure shows two separate thalli of the liverwort $Marchantia$.
One thallus bears the female reproductive structure called the archegoniophore (stri-janyu-dhani-dhar),while the other bears the male reproductive structure called the antheridiophore (pun-janyu-dhani-dhar).
Since the male and female reproductive organs are present on separate thalli,$Marchantia$ is dioecious or unisexual.
Therefore,the correct option is $B$.

(C) In biological life cycles,haploid $(n)$ structures contain a single set of chromosomes,while diploid $(2n)$ structures contain two sets of chromosomes.
$I$ - Zoospore: Haploid $(n)$
$II$ - Zygote: Diploid $(2n)$
$III$ - Egg cell: Haploid $(n)$
$IV$ - Gametophyte: Haploid $(n)$
$V$ - Sporophyte: Diploid $(2n)$
Therefore,the haploid structures are $I, III, IV$ and the diploid structures are $II, V$.

(A) Gametes are reproductive cells produced through meiosis, which reduces the chromosome number to half, making them $Haploid$ $(n)$.
When a male gamete $(n)$ and a female gamete $(n)$ fuse during fertilization, they form a $Zygote$ $(2n)$.
Therefore, the zygote is always $Diploid$ $(2n)$.
Thus, $P$ is $Haploid$ and $Q$ is $Diploid$.

(D) In asexual reproduction,a single parent produces offspring without the fusion of gametes.
Since there is no meiosis or fertilization involved,the offspring are genetically and morphologically identical to the parent,often referred to as clones.
Vegetative propagation is a specific type of asexual reproduction observed in plants.
Therefore,both asexual reproduction and vegetative propagation result in the formation of clones.

(C) $1$. Asexual reproduction is a mode of reproduction that does not involve the fusion of gametes or the change in the number of chromosomes. The offspring produced are genetically identical to the parent.
$2$. Sexual reproduction is a mode of reproduction that involves the fusion of male and female gametes to form a zygote,which eventually develops into a new organism.
$3$. Therefore,$P$ represents Asexual reproduction and $Q$ represents Sexual reproduction.

(C) Gametes are primarily formed in $Sexual$ reproduction through meiosis. However, in some cases of $Asexual$ reproduction, gametes can also be formed. For example, in honeybees, the male $(Drone)$ develops from an unfertilized egg (gamete) through a process called $Parthenogenesis$. Since the gamete is formed but does not undergo fusion, it is considered a form of asexual reproduction involving gamete formation.

(D) The lifespan of organisms is as follows:
$1$. Butterfly $(P)$: $1-2$ weeks $(III)$.
$2$. Crow $(Q)$: $15$ years $(IV)$.
$3$. Parrot $(R)$: $140$ years $(I)$.
$4$. Tortoise $(S)$: $100-150$ years $(II)$.
Therefore,the correct matching is $(P-III), (Q-IV), (R-I), (S-II)$.

(C) The term $Clones$ is used to describe individuals that are produced through asexual reproduction.
These individuals are exact copies of their parents.
Because they arise from a single parent without the fusion of gametes,they possess identical genetic material.
Furthermore,they exhibit the same physical characteristics as the parent.
Therefore,clones are defined as organisms that are both morphologically and genetically similar.

(B) Based on the provided images:
$P$ shows the zoospores of Chlamydomonas,which are motile structures.
$Q$ shows the conidia of Penicillium,which are non-motile spores produced in chains.
$R$ shows budding in Hydra,where a small outgrowth develops into a new individual.
$S$ shows gemmules in sponges,which are internal buds used for asexual reproduction.
Therefore,the correct matching is:
$P-II$
$Q-I$
$R-IV$
$S-III$
Thus,the correct option is $(P-II), (Q-I), (R-IV), (S-III)$.

(D) Under unfavorable conditions,$Amoeba$ withdraws its pseudopodia and secretes a three-layered hard covering or cyst around itself. This phenomenon is called encystation. When favorable conditions return,the encysted $Amoeba$ divides by multiple fission and produces many minute $Amoeba$ or pseudopodiospores. This process is known as sporulation.

(B) The correct matches are as follows:
$1$. Conidia $(P)$ are asexual reproductive structures found in fungi like $Penicillium$ $(II)$.
$2$. Buds $(Q)$ are small outgrowths that develop into new individuals,commonly seen in $Hydra$ $(I)$.
$3$. Gemmules $(R)$ are internal buds formed in sponges $(III)$ to survive unfavorable conditions.
Therefore,the correct matching is $P-II, Q-I, R-III$.

(D) Asexual reproduction involves a single parent and does not involve the fusion of gametes or meiosis.
As a result,the offspring produced are genetically identical to the parent,often referred to as clones.
Since there is no recombination of genetic material,it does not induce or maintain variation.
While mutations can occur,they are not the primary significance or purpose of asexual reproduction.
Therefore,none of the given options correctly describe the primary significance of asexual reproduction.

(B) In annual and biennial plants,the life cycle is completed within one or two years,respectively. Therefore,their vegetative,reproductive,and senescent phases are clearly distinct and observable.
In contrast,perennial plants live for many years. In many perennial species,the transition between vegetative,reproductive,and senescent phases is not clearly defined,as they may flower repeatedly over many years or have complex growth patterns.
Thus,$P$ represents Annual and Biennial plants,while $Q$ represents Perennial plants.

(A) Sexual reproduction in organisms is generally categorized into three distinct phases: Pre-fertilization,Fertilization,and Post-fertilization events.
$1$. Pre-fertilization events include gametogenesis (the formation of male and female gametes) and gamete transfer (the process of bringing gametes together for fusion).
$2$. Fertilization involves the fusion of male and female gametes to form a diploid zygote.
$3$. Post-fertilization events include the formation of the zygote and embryogenesis (development of the embryo).
Therefore,gametogenesis and gamete transfer are part of the pre-fertilization phase.

(A) In the given figure,the left side shows the heterogametes of the alga $Fucus$ (an egg and antherozoid).
The right side shows the heterogametes of humans (an ovum and sperms).
Therefore,the correct sequence is Heterogametes of $Fucus$ and Heterogametes of Human.

(D) In fungi and plants,the term 'bisexual' refers to the presence of both male and female reproductive structures on the same organism. For fungi,this is termed 'homothallic',and for plants,it is termed 'monoecious'.
Conversely,the 'unisexual' condition refers to the presence of male and female reproductive structures on separate organisms. For fungi,this is termed 'heterothallic',and for plants,it is termed 'dioecious'.
Therefore,$P$ (bisexual) corresponds to 'Homothallic,Monoecious' and $Q$ (unisexual) corresponds to 'Heterothallic,Dioecious'.

(C) Organisms belonging to Monera $(I)$,Fungi $(IV)$,Algae $(VIII)$,and Bryophytes $(II)$ are haploid $(n)$ in their vegetative phase. Therefore,they produce gametes through mitosis to maintain their ploidy level.
Organisms like Pteridophytes $(III)$,Gymnosperms $(V)$,Angiosperms $(VII)$,and Humans $(VI)$ are diploid $(2n)$ in their vegetative phase. Therefore,they undergo meiosis to produce haploid $(n)$ gametes.
Thus,the correct classification is:
- Mitosis: $I, II, IV, VIII$
- Meiosis: $III, V, VI, VII$
The correct option is $C$.

(B) To determine the chromosome number in gametes $(n)$,we divide the diploid chromosome number $(2n)$ by $2$.
$P$. Apple $(2n = 34)$: Gamete $(n)$ = $34/2 = 17$ $(IV)$.
$Q$. Rice $(2n = 24)$: Gamete $(n)$ = $24/2 = 12$ $(I)$.
$R$. Maize $(2n = 20)$: Gamete $(n)$ = $20/2 = 10$ $(II)$.
$S$. Potato $(2n = 48)$: Gamete $(n)$ = $48/2 = 24$ $(V)$.
$T$. Butterfly $(2n = 380)$: Gamete $(n)$ = $380/2 = 190$ $(III)$.
Thus,the correct matching is: $P-IV, Q-I, R-II, S-V, T-III$.

(A) The zygote is a vital link that ensures the continuity of species between organisms of one generation and the next.
$I -$ Zygote formation is a characteristic feature of sexual reproduction.
$II -$ Since it is formed by the fusion of two haploid gametes $(n + n)$,the zygote is always diploid $(2n)$.
$III -$ The zygote is commonly referred to as the fertilized egg.
$IV -$ It is the product of syngamy (fertilization).
$V -$ It acts as a bridge or link between two generations.
Therefore,all the given statements $(I, II, III, IV, V)$ are correct regarding the zygote.

(B) External fertilization occurs in water where gametes are released into the medium. This is observed in most Algae $(III)$,some Amphibians $(IX)$,and most Fish $(VIII)$.
Internal fertilization occurs inside the body of the organism. This is observed in Fungi $(I)$,Bryophytes $(IV)$,Pteridophytes $(V)$,Gymnosperms $(VI)$,Angiosperms $(VII)$,Reptiles $(X)$,Birds $(II)$,and Mammals $(XI)$.
Therefore,Internal fertilization: $I, II, IV, V, VI, VII, X, XI$ and External fertilization: $III, VIII, IX$.

(D) External fertilization is the process in which the fusion of gametes occurs outside the body of the organism,typically in an external medium like water.
$1$. Organisms exhibiting external fertilization (such as bony fishes and amphibians) release a large number of gametes to increase the chances of syngamy.
$2$. In this process,the probability of offspring being destroyed by predators is very high,which results in a lower survival rate to adulthood.
$3$. Water is an essential medium for this type of fertilization.
Therefore,all the given options are correct for external fertilization.

(D) Oviparous animals are those that lay eggs.
$1$. Reptiles and birds are classic examples of oviparous organisms.
$2$. These animals lay eggs protected by a hard calcareous (calcium-rich) shell in a safe environment to protect them from predators and environmental stress.
$3$. After a specific incubation period,the embryo develops and the young ones hatch out from the eggs.
Therefore,all the given statements are correct.

(D) $P$ refers to Asexual reproduction. In asexual reproduction,the offspring produced are genetically identical to the parent because there is no fusion of gametes or recombination of genetic material,thus preserving genetic information across generations.
$Q$ refers to Sexual reproduction. In sexual reproduction,the fusion of male and female gametes and the process of meiosis (crossing over) introduce genetic variations in the offspring,leading to diversity in traits.

(C) Some organisms breed only once in their lifetime,a phenomenon known as semelparity.
$I -$ Bamboo species are well-known for flowering and producing seeds only once in their lifetime after a long vegetative period.
$V -$ Pacific salmon fish migrate from the ocean to freshwater rivers to spawn and die shortly after,meaning they breed only once.
$II, III,$ and $IV$ (Birds,Mammals,and most Deep sea fish) are iteroparous,meaning they breed multiple times throughout their lifespan.
Therefore,the correct organisms are $I$ and $V$.

(B) The correct matches are as follows:
$1$. Chlamydomonas produces motile asexual spores called Zoospores $(a-ii)$.
$2$. Penicillium reproduces through asexual spores known as Conidia $(b-i)$.
$3$. Hydra reproduces by the formation of external Buds $(c-iv)$.
$4$. Sponges (like Sycon) reproduce through internal buds called Gemmules $(d-iii)$.
Therefore,the correct matching is $a-ii, b-i, c-iv, d-iii$.

(D) Clones are defined as individuals that are produced through asexual reproduction.
Since asexual reproduction involves only a single parent and does not involve meiosis or fertilization,the offspring produced are exact copies of the parent.
Therefore,these individuals are identical both morphologically (in terms of physical appearance) and genetically (in terms of $DNA$ sequence).

(A) The correct matches for the modes of asexual reproduction are as follows:
$1$. Yeast $(i)$ reproduces by budding $(c)$.
$2$. Penicillium $(ii)$ produces asexual spores called conidia $(d)$.
$3$. Filamentous algae $(iii)$ like Spirogyra reproduce by fragmentation $(a)$.
$4$. Chlamydomonas $(iv)$ produces motile asexual spores called zoospores $(b)$.
Therefore,the correct sequence is $i-c, ii-d, iii-a, iv-b$.

(D) Continuous breeders are animals that are sexually active throughout their reproductive phase,regardless of the season.
Examples include humans and apes.
Seasonal breeders,on the other hand,are reproductively active only during favorable seasons (e.g.,sheep,goats,and donkeys).
Therefore,the correct pair is apes and humans.