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CBSE Questions for Class 12 Medical Biology Reproduction In Organisms Quiz 8 - MCQExams.com
CBSE
Class 12 Medical Biology
Reproduction In Organisms
Quiz 8
Select the wrong statement :
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Chlamydomonas
exhibits both isogamy and anisogamy and Fucus shows oogamy.
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Isogametes are similar in structure, function and behaviour.
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Anisogametes differ either in structure, function or behaciour.
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In oomycetes, female gamete is smaller and motile while male gamete is larger and non-motile.
Which of the following cannot be seen during estrus cycle?
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Estrogen produces strong sex surge
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Menstruation at the end of the estrous cycle
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Ovulation takes place during estrus phase
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None of the above
Explanation
A
nimals that have
estrus cycles
resorb the endometrium if conception does not occur during that
cycle
.
Animals that have
menstrual cycles
shed the endometrium through
menstruation
if conception does not take place.
So, the correct option is 'Menstruation at the end of the estrus cycle'.
State whether the following statements are true or false, Frogs are not capable of internal fertilisation
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True
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False
Explanation
For salamanders and caecilian, internal fertilization is seen but external fertilization is found in frogs.
So the given statement is true
In oogamous reproduction,
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Both male and female gametes are motile
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Both gametes are product of division of protoplast
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Both male and female gametes are non-motile
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For male gametes protoplast divides but for female gamete it does not
Explanation
Oogamy is a system of sexual reproduction in which one gamete (called the egg) is large and nonmotile, while the other (called the sperm) is small and motile. Oogamy is a type of Anisogamy.
During Spermatogenesis, the protoplast of spermatogonium is equally divided into 4 spermatids while during oogenesis, ovum retains the bulk of protoplast and is minimally shared by Polar bodies.
So, the correct option is '
For male gametes protoplast divides but for female gamete it does not'.
Fusion between a larger non-motile (static) female gamete and smaller motile male gamete is
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Isogamous
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Oogamous
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Anisogamous
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Homogamous
Explanation
Isogamy is the fusion of gametes that are similar in similar sizes. Anisogamy involves fusion of gametes that are dissimilar in sizes where both gametes are either motile or immobile.
In oogamy, female gamete is static while male gamete is small and motile.
So, the correct option is 'Oogamous'.
Regeneration occurs in which of the following organisms?
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Planaria
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Hydra
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Saccharomyces
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Both A and B
Explanation
If the individual is cut or broken up into many pieces accidentally, these pieces can regrow into separate individuals. This is called regeneration.
Some species, like
Hydra
and
Planaria,
undergo regeneration.
Budding occurs in
Saccharomyces
(yeast).
So, the correct option is C.
Which one of the following methods requires two genetically variable individuals to produce the progeny?
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Cutting
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Layering
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Budding
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Goatee
A difference between estrous and menstrual cycles is that
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Non-mammalian vertebrates have estrous cycles, whereas mammals have menstrual cycles
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The endometrial lining is shed in menstrual cycles but reabsorbed in estrous cycles
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Estrous cycles occur more frequently than menstrual cycles do
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Ovulation occurs before the endometrium thickens in estrous cycles
Explanation
Menstrual cycle occurs in primates (monkeys, apes and human beings). This cycle consists of the menstrual phase, the proliferative phase and the secretory phase and the broken endometrium is passed out during menstruation. The oestrous cycle
occurs in non-primates such as cows, dogs, etc.
It consists of a short period of estrus or heat followed by anoestrus or passive period. The broken endometrium is reabsorbed during the oestrous cycle.
So the correct option is 'the endometrial lining is shed in menstrual cycles but reabsorbed in the oestrous cycle'.
Fusion of two gametes which are dissimilar in size is termed as
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Oogamy
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Isogamy
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Anisogamy
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Both A and C
Explanation
In anisogamy the fusing gametes differ in size and behaviour. One of the two gametes is larger and is called macrogamete or female gamete; the other is smaller and is termed microgamete or male gamete. In oogamy, there is a large food laden non-flagellate female gamete called egg or oosphere whereas the male gamete or antherozoid is smaller and motile. Oogamy is the familiar form of sexual reproduction, it is a form of anisogamy (heterogamy).
So, the correct answer is 'Both A and C'.
Which of the following characterizes parthenogenesis?
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An individual may change its sex during its lifetime
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Specialized groups of cells may be released and grow into new individuals
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An egg develops without being fertilized
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Both members of a mating pair have male and female reproductive organs
Explanation
Parthenogenesis, a reproductive strategy that involves the development of a female gamete (sex cell) without fertilization. An egg produced parthenogenetically may be either haploid (i.e., with one set of dissimilar chromosomes) or diploid (i.e., with a paired set of chromosomes). Parthenogenesis has received considerable attention as a tool for the production of stem cells. The possibility of deriving stem cells from parthenogenetic embryos could eliminate the requirement to produce and destroy viable embryos and may reduce the ethical concerns surrounding stem cell research.
So the correct option is 'an egg develops without being fertilized'.
Choose the correct answers from the alternatives given.
The principal embryonic membranes are
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Chorion and umbilicus
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Amnion and placenta
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Amnion and chorion
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Placenta and umbilicus
Explanation
The placenta is an ephemeral organ found only in eutherian mammals during gestation.
Placenta is the only organ composed of cells derived from two different organisms i.e. from the fetus and the mother.
The fetal membranes are chorion and amnion.
The membranes from the uterine wall are deciduas basalis. It is the portion of the deciduas which is directly adjacent to conception at the implantation site.
Decidua is a mucous membrane lining the uterus during pregnancy and it cast off during childbirth. After the implantation of the embryo, the uterine endometrium is called decidua. Thus the principal embryonic membranes are Amnion and chorion.
So the correct option is '
Amnion and chorion
'.
In maize, a meiocyte has $$20$$ chromosomes. What will be the number of chromosomes in its somatic cell?
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$$40$$
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$$30$$
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$$20$$
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$$10$$
Which of the following options show two plants in which new plantlets arise from the same organ?
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Dahlia and ginger
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Potato and sweet potato
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Dahlia and rose
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Potato and sugarcane
Explanation
New plantlets in potato and sugarcane arise from bud on stem. Potato have buds over their nodes or eyes.
The buds produce new plantlets when a part of its having a node is placed in the soil. Sugarcane is propagated by planting segments of stems having at least one node.
The vegetative propagation of
Dahlia
is done by tuberous roots. Tuberous roots have an abundant storage of reserved food material.
In ginger, the vegetative propagation occurs through the underground stem called a rhizome or by roots in sweet potato.
We propagate rose artificially through stem cuttings.
So, the correct option is D- Potato and sugarcane.
The limited period of sexual receptivity that occur around the time of ovulation in all female mammals, except human, is called
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Oogenesis
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Menstruation
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Estrus
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Puberty
Explanation
Estrus is the period in the sexual cycle of female mammals, except humans during which they are in heat, i.e ready to mate. Prior to ovulation, the endometrium (uterine lining) thickens, in preparation for holding the fertilized ova. As the proliferation of uterine tissue reaches its peak, receptivity is the highest which is called the oestrous period. The period of sexual receptivity is primarily initiated by the elevation in estrogens from mature follicles just prior to ovulation. The basic pattern of the oestrous cycle is the same in all domestic animals, but some specific differences are found in specific parts of the cycle.
So the correct option is 'estrus'.
Name the process in which thousands of plants can be raised within a limited time and space.
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Pathernocarpy
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Self pollination
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Tissue culture
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Water
Explanation
The process by which thousands of plants can be raised within a limited time and space is Tissue culture.
The process of growing new plants from a small piece of plant tissue or cells removed from the growing tips of a plant in a suitable growth medium, is called tissue culture.
Its advantages are:
1) Thousands
of plantlets can be produced in a very less time from a small amount of plant tissue.
2) Very little space is needed for developing new plants.
3) The plants produced are disease-free.
Choose the correct statements from the options below with regard to sexual reproduction in plants.
(i) Sexual reproduction does not always require two individuals.
(ii) Sexual reproduction generally involves gametic fusion.
(iii) Meiosis never occurs during sexual reproduction.
(iv) External fertilization is a rule during sexual reproduction.
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(i) and (iv)
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(i) and (ii)
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(ii) and (iii)
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(ii) and (iv)
Explanation
(i) Sexual reproduction does not require two individuals because the fusion of two gametes released from the same plant can take place.
(ii) Sexual reproduction is a process where gametic fusion takes place between two gametes of different sexes.
(iii) Meiosis occurs during sexual reproduction to produce haploid gametes.
(iv) External fertilization need not take place in sexual reproduction. It can also be internal. Eg: humans.
So, the correct option is '(i) and (ii)'.
A phenomenon is termed as parthenogenesis when
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Artificial fertilization occurs
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Egg is fertilized by a sperm
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Egg undergoes cleavage without fertilization
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Sperm dies before fertilization
Explanation
The term parthenogenesis was coined by Charles Bonnet. It is also called the virgin birth. Parthenogenesis refers to the process of formation of the organism from an unfertilized egg (it is a special type of asexual reproduction). Parthenogenesis is of the following three types:
1) Arrhenotoky: male develops parthenogenically.
2) Thelytoky: Female develops parthenogenically.
3) Amphytoky: Parthenogenesis results in any sex depending on environmental conditions.
So, considering all the information the correct answer is 'Egg undergoes cleavage without fertilization'.
Which among the following statements are true for unisexual flowers?
(i) They possess both stamen and pistil.
(ii) They possess either stamen or pistil.
(iii) They exhibit cross pollination.
(iv) Unisexual flowers possessing only stamens cannot produce fruits.
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(i) and (iv)
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(ii), (iii) and (iv)
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(iii) and (iv)
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(i), (iii) and (iv)
Explanation
In angiosperms, flowers can be unisexual having either stamen or pistil; or bisexual having both stamen and pistil in the same flower.
In both types of flowers, Pistil bears ovary.
Since unisexual flowers have either male or female sexual organs. Therefore, they cannot self-pollinate and, thus, show cross-pollination
Fruit is ripened or mature ovary.
After fertilization ovary undergoes major changes and its wall also thickens to produce fruit. That means a staminate flower (flower with only stamens) cannot produce fruits.
Therefore, the correct answer is option B.
The following graph shows the levels of pituitary hormones during a menstrual cycle. What do 1 and 2 represent?
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1-LH, 2-FSH
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1- Estrogen, 2-Progesterone
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1-FSH, 2-LH
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1-Progesterone, 2-Estrogen
Bryophyllum reproduces vegetatively through _________.
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Leaf
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Root
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Stem
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Flower
Explanation
$$\textbf{Correct Option A}$$
$$\textbf{Solution}$$
$$\bullet$$ Reproduction in bryophyllum occurs through asexual medium by vegetative propagation of leaves. The leaf part of the bryophyllum have notches at its margin which contains buds that are called epiphyllous buds.
$$\bullet$$
These buds present at the notch detaches from the leaves and falls on the ground. After this the buds grow to produce new bryophyllum plants by giving rise to adventitious roots and small leaves.
$$\bullet$$
The grow up and become a mature plant after coming in contact with the ground.
$$\bullet$$ So, the correct option is A.
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