Assertion (A): Reproduction is essential for the continuation
of species. Reason (R): Reproduction helps in the transfer of genetic
material from one generation to the next. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Reproduction ensures the survival and continuity
of species by transferring genetic material across generations.
Assertion (A): Asexual reproduction is more common in lower
organisms. Reason (R): Asexual reproduction requires only one parent. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: In lower organisms like bacteria, asexual
reproduction is favored as it is simple and requires only one parent.
Assertion (A): In binary fission, the parent cell divides into
two equal parts. Reason (R): Binary fission is a type of asexual reproduction. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: In binary fission, the parent cell divides into
two equal daughter cells, and this is an asexual mode of reproduction.
Assertion (A): In budding, the parent organism develops a small
outgrowth. Reason (R): The outgrowth detaches from the parent to form a
new organism. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Budding is a form of asexual reproduction where a
new organism forms as a bud on the parent and later detaches.
Assertion (A): The Zygote is the first cell of a new organism. Reason (R): A zygote is formed by the fusion of male and female
gametes during sexual reproduction. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: The zygote forms when the sperm and egg fuse, and
it is the initial cell of the offspring.
Assertion (A): In plants, vegetative propagation is a form of
asexual reproduction. Reason (R): Vegetative parts like stems, leaves, and roots can
develop into new plants. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Vegetative propagation uses parts of the plant
other than seeds for reproduction, making it an asexual process.
Assertion (A): Fertilization results in the formation of a
zygote. Reason (R): Fertilization involves the fusion of male and
female gametes. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Fertilization is the fusion of male and female
gametes, forming a zygote.
Assertion (A): The male gamete is smaller and motile, whereas
the female gamete is larger and non-motile. Reason (R): The male gamete (sperm) is designed for mobility,
while the egg provides nutrition for the developing embryo. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: The sperm’s small size and motility help it reach
the egg, while the egg’s larger size provides nutrients for the developing
organism.
Assertion (A): In external fertilization, gametes are released
into the environment. Reason (R): External fertilization is common in aquatic
organisms like fish and amphibians. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: External fertilization occurs in the water, where
gametes are released into the surrounding medium to meet and fertilize.
Assertion (A): Internal fertilization is more common in
terrestrial animals. Reason (R): Internal fertilization provides a protected
environment for the fertilized egg. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Internal fertilization is a strategy to ensure the
protection of the fertilized egg in terrestrial environments.
Assertion (A): Male and female gametes are haploid. Reason (R): Haploid cells contain half the number of
chromosomes compared to diploid cells. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Gametes are haploid because they contain half the
number of chromosomes, which will be restored to diploid after fertilization.
Assertion (A): In sexual reproduction, the fusion of male and
female gametes results in the formation of a zygote. Reason (R): The zygote develops into an organism through
mitotic division. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: After fertilization, the zygote divides by mitosis
to form a multicellular organism.
Assertion (A): In asexual reproduction, offspring are
genetically identical to the parent. Reason (R): Asexual reproduction involves only one parent, with
no genetic recombination. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Asexual reproduction results in offspring
genetically identical to the parent due to no genetic recombination.
Assertion (A): Sexual reproduction results in genetic
variation. Reason (R): Meiosis and fertilization increase genetic
diversity by producing unique combinations of alleles. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Sexual reproduction involves meiosis and
fertilization, which contribute to genetic variation in offspring.
Assertion (A): Regeneration is a type of asexual reproduction
in some organisms. Reason (R): In regeneration, the organism regrows lost parts or
forms a new organism from a part of the parent. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Some organisms can regenerate lost parts, and
these parts may develop into new individuals, making regeneration a form of
asexual reproduction.
Assertion (A): In parthenogenesis, offspring are produced from
an unfertilized egg. Reason (R): Parthenogenesis is an asexual form of reproduction
where no fertilization is involved. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Parthenogenesis is a process in which offspring
develop from an unfertilized egg, thus occurring without fertilization.
Assertion (A): Fragmentation is a mode of asexual reproduction. Reason (R): Fragmentation involves the breaking of the organism
into pieces, each capable of developing into a new individual. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Fragmentation occurs when a parent organism breaks
into pieces, and each piece can regenerate into a new individual.
Assertion (A): Spermatogenesis involves the formation of male
gametes. Reason (R): Spermatogenesis occurs in the seminiferous tubules
of the testes. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Spermatogenesis is the process of producing sperm,
which occurs in the seminiferous tubules of the testes.
Assertion (A): Oogenesis is the process of egg formation. Reason (R): Oogenesis occurs in the ovaries and results in the
formation of a single mature egg. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Oogenesis is the process of egg formation, and it
takes place in the ovaries, producing a single egg from several stages of cell
division.
Assertion (A): In human males, the sperm is produced throughout
life after puberty. Reason (R): Spermatogenesis is a continuous process in males
once puberty is reached. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: In males, spermatogenesis begins at puberty and
continues throughout life, producing sperm continuously.
Assertion (A): In human females, oogenesis starts before birth. Reason (R): Oogenesis in females is initiated in the fetal
stage but completes only after puberty. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Oogenesis starts during fetal development, but the
process is arrested until puberty, when it continues.
Assertion (A): The female reproductive system is cyclic in
nature. Reason (R): Menstrual cycles regulate ovulation and the
preparation of the uterine lining for pregnancy. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: The menstrual cycle regulates ovulation and
prepares the uterine lining for implantation, making the female reproductive
system cyclic.
Assertion (A): The placenta is an organ that facilitates the
exchange of gases, nutrients, and wastes between the mother and the fetus. Reason (R): The placenta is connected to the fetus by the
umbilical cord. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: The placenta serves as the interface for nutrient
and gas exchange, and the umbilical cord connects the fetus to the placenta.
Assertion (A): The menstrual cycle is divided into phases. Reason (R): The phases of the menstrual cycle include the
follicular phase, ovulation, luteal phase, and menstruation. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: The menstrual cycle is divided into phases that
regulate ovulation and menstruation, ensuring reproductive readiness.
Assertion (A): Fertilization in humans occurs in the fallopian
tubes. Reason (R): The sperm must travel through the cervix and uterus
to reach the fallopian tube. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: In humans, fertilization occurs when the sperm
reaches the fallopian tube, where the egg is awaiting fertilization.
Assertion (A): The process of fertilization in humans involves
the fusion of sperm and egg. Reason (R): The fertilized egg undergoes cleavage to form a
blastocyst, which implants in the uterine wall. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Fertilization involves the fusion of sperm and
egg, and the resulting zygote undergoes cleavage to form a blastocyst, which
implants in the uterus.
Assertion (A): In humans, the fertilization of the egg occurs
in the fallopian tube. Reason (R): The sperm enters the uterus and travels to the
fallopian tube where it meets the egg. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Fertilization takes place in the fallopian tube,
where the sperm meets the egg after traveling through the uterus.
Assertion (A): Asexual reproduction leads to offspring that are
genetically identical to the parent. Reason (R): Asexual reproduction does not involve the fusion of
gametes and thus no genetic variation occurs. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Since asexual reproduction does not involve gamete
fusion, the offspring are genetically identical to the parent.
Assertion (A): The male reproductive system produces both sperm
and hormones. Reason (R): The testes produce sperm and also secrete
testosterone, which regulates male reproductive functions. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: The testes produce both sperm and testosterone,
which is vital for the regulation of male reproductive functions.
Assertion (A): The fertilized egg undergoes several divisions
to form a blastocyst. Reason (R): The blastocyst implants into the uterus, beginning
the development of the embryo. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: After fertilization, the zygote divides and forms
a blastocyst, which then implants in the uterine lining for embryo development.
Assertion (A): Menstruation is the shedding of the uterine
lining. Reason (R): Menstruation occurs if fertilization does not take
place, leading to the breakdown and expulsion of the uterine lining. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: If fertilization does not occur, the uterine
lining breaks down and is shed during menstruation.
Assertion (A): Sexual reproduction involves the fusion of two
haploid gametes to form a diploid zygote. Reason (R): Sexual reproduction requires two parents to
contribute their gametes to the offspring. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: In sexual reproduction, haploid gametes from two
parents fuse to form a diploid zygote, which develops into a new individual.
Assertion (A): The primary function of the male reproductive
system is the production of sperm. Reason (R): The testes produce sperm and also secrete hormones
like testosterone. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: The testes produce both sperm and testosterone,
which is essential for the regulation of male reproductive functions.
Assertion (A): The uterus is where the fertilized egg develops
into an embryo. Reason (R): The fertilized egg embeds itself in the uterine
lining, where it undergoes development. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: After fertilization, the egg implants into the
uterine lining, where it undergoes development into an embryo.
Assertion (A): Asexual reproduction is more rapid than sexual
reproduction. Reason (R): Asexual reproduction requires only one parent and
does not involve complex processes like gamete fusion. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Asexual reproduction is faster because it does not
require the formation and fusion of gametes, unlike sexual reproduction.
Assertion (A): Parthenogenesis is a type of asexual
reproduction. Reason (R): In parthenogenesis, offspring are produced from an
unfertilized egg. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Parthenogenesis is a form of asexual reproduction
where offspring develop from unfertilized eggs.
Assertion (A): Regeneration in organisms like planaria is a
form of asexual reproduction. Reason (R): In regeneration, a part of the organism can grow
into a completely new individual. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Regeneration allows organisms to grow new
individuals from body parts, making it a form of asexual reproduction.
Assertion (A): The process of fertilization is essential for
sexual reproduction. Reason (R): Fertilization restores the diploid chromosome
number in the zygote. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Fertilization combines two haploid gametes,
restoring the diploid chromosome number in the zygote.
Assertion (A): Male gametes are motile and smaller than female
gametes. Reason (R): Sperm have a flagellum that enables them to move
toward the egg. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Sperm are smaller and motile, with a flagellum
that helps them move toward the egg during fertilization.
Assertion (A): In humans, sperm production occurs in the
testes. Reason (R): The testes contain seminiferous tubules, which are
responsible for sperm production. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Sperm are produced in the seminiferous tubules of
the testes, which is the primary location for spermatogenesis.
Assertion (A): In human females, the number of eggs is fixed at
birth. Reason (R): Oogenesis starts during fetal development but
arrests at a certain stage until puberty. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Human females are born with a fixed number of
eggs, and oogenesis begins in fetal development but is paused until puberty.
Assertion (A): External fertilization is common in aquatic
organisms. Reason (R): Water provides a medium where sperm can swim to
reach eggs. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: External fertilization occurs in aquatic
environments, where sperm can easily travel to eggs in the surrounding water.
Assertion (A): Oogenesis results in the formation of a single
egg from each primary oocyte. Reason (R): The process of oogenesis includes asymmetric
division, where one cell gets most of the cytoplasm. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: In oogenesis, each primary oocyte gives rise to
one mature egg and smaller polar bodies, through asymmetric cell division.
Assertion (A): The fertilized egg divides to form a blastocyst. Reason (R): The blastocyst consists of an inner cell mass and
trophoblast cells. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: After fertilization, the egg divides, forming a
blastocyst, which consists of an inner cell mass (embryo) and trophoblast
(placental tissue).
Assertion (A): Menstruation is a sign that pregnancy has not
occurred. Reason (R): If the egg is not fertilized, the corpus luteum
degenerates, leading to a drop in progesterone levels. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Without fertilization, progesterone levels fall,
leading to the shedding of the uterine lining, which is menstruation.
Assertion (A): Sperm are produced continuously in males after
puberty. Reason (R): Spermatogenesis is a continuous process in the
seminiferous tubules. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: In males, sperm are produced continuously in the
seminiferous tubules throughout adulthood after puberty.
Assertion (A): The fertilization process is completed when the
sperm fuses with the egg membrane. Reason (R): The sperm’s acrosomal enzymes help it penetrate the
egg’s outer layers. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: The sperm uses its acrosomal enzymes to penetrate
the egg’s outer membrane, completing fertilization.
Assertion (A): All offspring of asexual reproduction are
genetically identical to the parent. Reason (R): Asexual reproduction does not involve genetic
recombination. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Asexual reproduction does not involve the mixing
of genetic material, resulting in offspring that are genetically identical to
the parent.
Assertion (A): Reproduction is essential for the continuation
of a species. Reason (R): Reproduction ensures the transfer of genetic
material to the next generation. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Reproduction ensures that genetic material is
passed to the next generation, ensuring the survival of the species.
Assertion (A): Reproduction in organisms can be both sexual and
asexual. Reason (R): Asexual reproduction does not require the fusion of
gametes, whereas sexual reproduction does. Answer: (A) Both A and R are true, and R is the correct
explanation of A. Explanation: Asexual reproduction occurs without the need for
gametes, while sexual reproduction involves the fusion of male and female
gametes.