Dedifferentiated mass of the cell

Organisms: Crow , Lifespan: 15 Years

Organisms: Parrot , Lifespan: 140 Years

Organisms: Butterfly , Lifespan: 1 to 2 Weeks

Morphologically similar individuals

Genetically similar individuals

REPRODUCTION IN ORGANISMS MCQs for NEET UG BIOLOGY — Medium

1 Medium

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Transverse binary fission occurs in

View answer and explanation

Correct option: D

Paramecium

Option D (Paramecium) is correct because Paramecium divides transversely during binary fission, meaning the division occurs across the width of the cell.

Solution approach

Correct Answer + Core Reason: Paramecium. Transverse binary fission occurs in Paramecium.

Step-by-Step Solution:

Step 1: Recall the different types of binary fission.

Step 2: Identify transverse binary fission as a characteristic of Paramecium.

Step 3: Recognize that transverse division occurs across the width of the cell.

Step 4: Conclude that Paramecium is the correct answer.

Why other options are wrong:
- Option A: Euglena undergoes longitudinal binary fission.
- Option B: Amoeba undergoes binary fission in no specific plane.
- Option C: Hydra reproduces by budding, not binary fission.
- Option D: Paramecium undergoes transverse binary fission.

Key Concepts:
- Asexual reproduction
- Binary fission
- Transverse binary fission
- Paramecium reproduction

Memory Aids:
- Think of \"transverse\" as \"across,\" referring to the division plane in Paramecium.

Quick Tips:
- Consider the specific orientation of cell division in different organisms.

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Find out the number of chromosomes present in meiocytes of Dog, Rat, Rice, Potato?

View answer and explanation

Correct option: C

78,42,24,48

Option C is correct because it lists the correct number of chromosomes in the meiocytes (diploid cells undergoing meiosis) of Dog (78), Rat (42), Rice (24), and Potato (48).

Solution approach

Correct Answer + Core Reason: 78, 42, 24, 48. These are the correct diploid chromosome numbers for Dog, Rat, Rice, and Potato respectively.

Step-by-Step Solution:
Step 1: Recall the diploid chromosome number (2n) for each organism:
- Dog: 2n = 78
- Rat: 2n = 42
- Rice: 2n = 24
- Potato: 2n = 48
Step 2: Match the chromosome numbers with the organisms.

Why other options are wrong:
- Option A: 78, 36, 24, 24. Rat and Potato chromosome numbers are incorrect.
- Option B: 78, 42, 48, 24. Potato chromosome number is incorrect.
- Option D: 34, 48, 24, 78. Dog and Rat chromosome numbers are incorrect.

Key Concepts:
- Chromosome number
- Diploid (2n)
- Meiocytes

Memory Aids:
- Remember common chromosome numbers for model organisms.

Quick Tips:
- Memorize the chromosome numbers of common organisms.

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Callus is a

View answer and explanation

Correct option: D

Undifferentiated mass of the cell

Option D is correct because callus is an unorganized, undifferentiated mass of cells formed during tissue culture.

Solution approach

Correct Answer + Core Reason: Undifferentiated mass of the cell. Callus is a mass of undifferentiated cells.

Step-by-Step Solution:
Step 1: Define callus: Callus is a mass of undifferentiated plant cells (parenchyma) that forms in response to wounding or in tissue culture.
Step 2: Explain the term "undifferentiated": Undifferentiated cells have not yet specialized into specific cell types (e.g., xylem, phloem).

Why other options are wrong:
- Option A: Organized mass of the cell. Callus is unorganized.
- Option B: Differentiated mass of the cell. Callus is undifferentiated.
- Option C: Dedifferentiated mass of the cell. While cells in a callus may have dedifferentiated, the callus itself is primarily undifferentiated.

Key Concepts:
- Callus
- Tissue culture
- Cell differentiation

Memory Aids:
- Callus = Undifferentiated

Quick Tips:
- Remember that callus formation is a key step in plant tissue culture.

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(A): Algae and fungi switch to asexual method of reproduction before the onset of adverse conditions

(R): Asexual reproduction may introduce variations and leads to the formation of many clones

View answer and explanation

Correct option: D

Both (A) and (R) are false.

Option D (Both (A) and (R) are false) is correct because algae and fungi typically switch to asexual reproduction during FAVORABLE conditions, and asexual reproduction produces clones, which have limited variation.

Solution approach

Correct Answer + Core Reason: Both (A) and (R) are false. Algae and fungi switch to asexual reproduction during favorable conditions, and asexual reproduction produces clones with limited variation.

Step-by-Step Solution:

Step 1: Analyze the assertion (A) and the reason (R).

Step 2: Assertion (A) is false: Algae and fungi typically switch to asexual reproduction during FAVORABLE conditions when resources are abundant and the environment is stable. During adverse conditions, some may undergo sexual reproduction to increase genetic diversity.

Step 3: Reason (R) is false: Asexual reproduction produces clones, which are genetically identical or very similar to the parent. Therefore, it introduces limited variation compared to sexual reproduction.

Step 4: Since both the assertion and the reason are false, the correct option is D.

Why other options are wrong:
- Option A: Both (A) and (R) are true and (R) is the correct explanation of (A) is incorrect because both A and R are false.
- Option B: Both (A) and (R) are true and (R) is not the correct explanation of (A) is incorrect because both A and R are false.
- Option C: (A) is true but (R) is false is incorrect because both A and R are false.

Key Concepts:
- Asexual reproduction
- Sexual reproduction
- Genetic variation
- Environmental conditions

Memory Aids:
- Asexual: Favorable conditions, limited variation
- Sexual: Adverse conditions, increased variation

Quick Tips:
- Remember the conditions that favor asexual and sexual reproduction.

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The staminate and pistillate flowers are found on separate plant body in

View answer and explanation

Correct option: A

Date palm

Option A (Date palm) is correct because date palms are dioecious, meaning they have separate staminate (male) and pistillate (female) flowers on different plants.

Solution approach

Correct Answer + Core Reason: Date palm. Date palms are dioecious, having separate male and female plants.

Step-by-Step Solution:

Step 1: Define staminate and pistillate flowers.

Step 2: Staminate flowers are male flowers, and pistillate flowers are female flowers.

Step 3: Consider the options:
- Date palm: Dioecious (separate male and female plants).
- Cucurbits: Monoecious (male and female flowers on the same plant).
- Maize: Monoecious (male and female flowers on the same plant).
- Coconut: Monoecious (male and female flowers on the same plant).

Why other options are wrong:
- Option B: Cucurbits are monoecious, meaning they have both male and female flowers on the same plant.
- Option C: Maize is monoecious, meaning it has both male and female flowers on the same plant.
- Option D: Coconut is monoecious, meaning it has both male and female flowers on the same plant.

Key Concepts:
- Staminate flower
- Pistillate flower
- Dioecious
- Monoecious

Memory Aids:
- Dioecious: Di- (two) - separate houses (plants) for male and female flowers.
- Monoecious: Mono- (one) - one house (plant) for both male and female flowers.

Quick Tips:
- Remember the difference between monoecious and dioecious plants.

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Cell Division is itself a type of reproduction in?

View answer and explanation

Correct option: A

Euglena

Option A (Euglena) is correct because Euglena is a unicellular organism where cell division (binary fission) is its primary mode of reproduction.

Solution approach

Correct Answer + Core Reason: Euglena. In unicellular organisms like Euglena, cell division is reproduction.

Step-by-Step Solution:

Step 1: Consider the definition of reproduction: The process by which an organism produces offspring.

Step 2: In unicellular organisms, cell division (e.g., binary fission) results in the creation of new individuals. Therefore, cell division is a form of reproduction.

Step 3: Euglena is a unicellular organism that reproduces by binary fission.

Step 4: Penicillium and Rhizopus are fungi that reproduce through spores.

Step 5: Liverworts are plants that reproduce both sexually and asexually (e.g., fragmentation, gemmae).

Why other options are wrong:
- Option B: Penicillium is incorrect because it reproduces through spores, not solely by cell division.
- Option C: Rhizopus is incorrect because it reproduces through spores, not solely by cell division.
- Option D: Liver Worts is incorrect because they reproduce sexually and asexually, but cell division is not their primary mode of reproduction.

Key Concepts:
- Reproduction in unicellular organisms
- Binary fission
- Asexual reproduction

Memory Aids:
- Unicellular = Cell division is reproduction

Quick Tips:
- Remember that in unicellular organisms, cell division is a form of reproduction.

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In which one pair, both the plants can be vegetatively propagated by leaf pieces?

View answer and explanation

Correct option: A

Bryophyllum and kalanchoe

Option A (Bryophyllum and kalanchoe) is correct because both these plants have leaves with buds that can develop into new plants.

Solution approach

Correct Answer + Core Reason: Bryophyllum and kalanchoe. Both plants can propagate vegetatively through leaf pieces due to the presence of adventitious buds on their leaves.

Step-by-Step Solution:

Step 1: Recall the concept of vegetative propagation through leaves.

Step 2: Identify plants known for leaf propagation.

Step 3: Recognize that Bryophyllum and Kalanchoe have notches on their leaves where buds develop.

Step 4: Conclude that Bryophyllum and Kalanchoe is the correct answer.

Why other options are wrong:
- Option B: Chrysanthemum and Agave do not typically propagate through leaf pieces.
- Option C: Agave and kalanchoe - Agave does not typically propagate through leaf pieces.
- Option D: Asparagus and Bryophyllum - Asparagus does not typically propagate through leaf pieces.

Key Concepts:
- Vegetative propagation
- Leaf propagation
- Adventitious buds

Memory Aids:
- Remember Bryophyllum and Kalanchoe for leaf propagation.

Quick Tips:
- Focus on plants with specialized structures for vegetative propagation.

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Binary fission is the mode of asexual reproduction in

View answer and explanation

Correct option: C

Both (1) and (2)

Option C (Both (1) and (2)) is correct because both Amoeba and Paramecium reproduce asexually through binary fission, where the cell divides into two identical daughter cells.

Solution approach

Correct Answer + Core Reason: Both (1) and (2). Binary fission is a mode of asexual reproduction in both Amoeba and Paramecium.

Step-by-Step Solution:

Step 1: Recall the asexual reproduction methods in Amoeba and Paramecium.

Step 2: Identify binary fission as a common method in both organisms.

Step 3: Recognize that binary fission involves cell division into two identical daughter cells.

Step 4: Conclude that both (1) and (2) is the correct answer.

Why other options are wrong:
- Option A: Amoeba does reproduce by binary fission, but this option is incomplete as Paramecium also does.
- Option B: Paramecium does reproduce by binary fission, but this option is incomplete as Amoeba also does.
- Option C: Both (1) and (2) is the correct answer as both Amoeba and Paramecium reproduce by binary fission.
- Option D: Yeast primarily reproduces by budding, not binary fission.

Key Concepts:
- Asexual reproduction
- Binary fission
- Amoeba reproduction
- Paramecium reproduction

Memory Aids:
- Think of \"binary\" as \"two,\" referring to the two daughter cells formed in binary fission.

Quick Tips:
- Consider the specific reproductive methods of different unicellular organisms.

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Asexual reproduction is a method of reproduction in which participation of ……… takes place

View answer and explanation

Correct option: A

One individual

Option A (One individual) is correct because asexual reproduction involves a single parent organism producing offspring that are genetically identical to itself.

Solution approach

Correct Answer + Core Reason: One individual. Asexual reproduction involves the participation of one individual.

Step-by-Step Solution:

Step 1: Recall the definition of asexual reproduction.

Step 2: Identify that asexual reproduction involves a single parent.

Step 3: Recognize that offspring are genetically identical to the parent.

Step 4: Conclude that one individual is the correct answer.

Why other options are wrong:
- Option B: Two individuals are involved in sexual reproduction, not asexual reproduction.
- Option C: Multi-individuals is not a term used to describe asexual reproduction.
- Option D: Meiosis is a process involved in sexual reproduction, not asexual reproduction.

Key Concepts:
- Asexual reproduction
- Sexual reproduction
- Genetic inheritance

Memory Aids:
- Think of \"a-\" as \"without,\" meaning without two parents in asexual reproduction.

Quick Tips:
- Distinguish between asexual and sexual reproduction based on the number of parents involved.

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Chromosome number in meiocyte of “A” plant, chromosome number in meiocyte of “B” plant are found in 1 : 2 ratio. Find out the A, B plants.

View answer and explanation

Correct option: B

A–Rice, B–Potato

Option B (A–Rice, B–Potato) is correct because Rice has a lower chromosome number than Potato, fitting the 1:2 ratio in their meiocytes.

Solution approach

Correct Answer + Core Reason: A–Rice, B–Potato. Rice has a lower chromosome number than Potato, fitting the 1:2 ratio.

Step-by-Step Solution:

Step 1: Recall the chromosome numbers of common plants.

Step 2: Rice has a diploid chromosome number (2n) of 24. Therefore, its meiocyte has 24 chromosomes.

Step 3: Potato has a diploid chromosome number (2n) of 48. Therefore, its meiocyte has 48 chromosomes.

Step 4: Calculate the ratio of chromosome numbers in meiocytes of Rice and Potato: 24 : 48 = 1 : 2.

Step 5: Compare this ratio with the given ratio of 1 : 2. The ratio matches, with A being Rice and B being Potato.

Why other options are wrong:
- Option A (A–Potato, B–Rice): Incorrect because this would give a ratio of 2:1, not 1:2.
- Option C (A–Maize, B–Rice): Incorrect because Maize (2n=20) and Rice (2n=24) do not have a 1:2 ratio.
- Option D (A–Apple, B–Onion): Incorrect because Apple (2n=34) and Onion (2n=16) do not have a 1:2 ratio.

Key Concepts:
- Chromosome Number
- Meiocyte
- Diploid Number (2n)

Memory Aids:
- Remember common plant chromosome numbers.

Quick Tips:
- Knowing the chromosome numbers of common plants is helpful for these types of questions.

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Find the mismatch.

View answer and explanation

Correct option: C

Organisms: Crocodile , Lifespan: 600 Years

Option C (Organisms: Crocodile , Lifespan: 600 Years) is the mismatch because the lifespan of a crocodile is typically around 70-100 years, not 600 years.

Solution approach

Correct Answer + Core Reason: Organisms: Crocodile , Lifespan: 600 Years. The lifespan of a crocodile is not 600 years.

Step-by-Step Solution:

Step 1: Crow lifespan is around 15 years.

Step 2: Parrot lifespan is around 140 years.

Step 3: Crocodile lifespan is around 70-100 years.

Step 4: Butterfly lifespan is around 1 to 2 weeks.

Why other options are wrong:
- Option A: Organisms: Crow , Lifespan: 15 Years: Correct match.
- Option B: Organisms: Parrot , Lifespan: 140 Years: Correct match.
- Option D: Organisms: Butterfly , Lifespan: 1 to 2 Weeks: Correct match.

Key Concepts:
- Lifespan of organisms

Memory Aids:
- Remember approximate lifespans of common animals.

Quick Tips:
- Consider the size and complexity of the organism when estimating lifespan.

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Clones are

View answer and explanation

Correct option: C

Both (1) and (2)

Option C (Both (1) and (2)) is correct because clones are individuals that are both morphologically (physically) and genetically identical.

Solution approach

Correct Answer + Core Reason: Both (1) and (2). Clones are morphologically and genetically similar.

Step-by-Step Solution:

Step 1: Define a clone: A clone is an individual that is genetically identical to its parent and to other individuals produced by the same asexual reproduction event.

Step 2: Clones are morphologically similar because they have the same genetic makeup, which determines their physical characteristics.

Step 3: Clones are genetically similar because they are produced by asexual reproduction, which does not involve the mixing of genetic material from two parents.

Step 4: Therefore, clones are both morphologically and genetically similar.

Why other options are wrong:
- Option A: Morphologically similar individuals is incorrect because clones are also genetically similar.
- Option B: Genetically similar individuals is incorrect because clones are also morphologically similar.
- Option D: None of the above is incorrect because clones are both morphologically and genetically similar.

Key Concepts:
- Clone
- Asexual reproduction
- Genetic similarity
- Morphological similarity

Memory Aids:
- Clones: Genetically and Morphologically Identical

Quick Tips:
- Remember that clones are produced by asexual reproduction.

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In which type of organism asexual reproduction is seen?

View answer and explanation

Correct option: D

1 and 3

Option D (1 and 3) is correct because asexual reproduction is commonly seen in both unicellular and multicellular organisms.

Solution approach

Correct Answer + Core Reason: 1 and 3. Asexual reproduction is seen in both unicellular and multicellular organisms.

Step-by-Step Solution:

Step 1: Define asexual reproduction: A mode of reproduction that does not involve the fusion of gametes.

Step 2: Asexual reproduction is common in unicellular organisms (e.g., bacteria, amoeba) through binary fission, budding, etc.

Step 3: Asexual reproduction is also seen in multicellular organisms (e.g., plants through vegetative propagation, some animals through fragmentation).

Step 4: Therefore, asexual reproduction is seen in both unicellular and multicellular organisms.

Why other options are wrong:
- Option A: unicellular is incorrect because asexual reproduction is also seen in multicellular organisms.
- Option B: bicellular is incorrect because bicellular is not a recognized category, and asexual reproduction is seen in unicellular and multicellular organisms.
- Option C: multicellular is incorrect because asexual reproduction is also seen in unicellular organisms.

Key Concepts:
- Asexual reproduction
- Unicellular organisms
- Multicellular organisms

Memory Aids:
- Asexual reproduction: No fusion of gametes

Quick Tips:
- Remember that asexual reproduction is not limited to unicellular organisms.

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Immortal individuals are

View answer and explanation

Correct option: A

Single celled organisms

Option A is correct because single-celled organisms that reproduce by binary fission are considered immortal as their cellular material is passed on to daughter cells.

Solution approach

Correct Answer + Core Reason: Single celled organisms. Due to reproduction by division, the parent cell's material is passed on.

Step-by-Step Solution:
Step 1: Understand the concept of immortality in the context of cell division. In single-celled organisms that reproduce by binary fission, the parent cell divides into two daughter cells, effectively continuing its lineage.
Step 2: Consider the other options:
- Double celled organisms: Not a standard biological term.
- Multi-celled organisms: Undergo aging and death.
- Green plants: Undergo aging and death.

Why other options are wrong:
- Option B: Double celled organisms is not a biologically relevant term.
- Option C: Multi-celled organisms undergo aging and death.
- Option D: Green plants undergo aging and death.

Key Concepts:
- Immortality in single-celled organisms
- Binary fission

Memory Aids:
- Single-celled = potential for immortality through division.

Quick Tips:
- Remember that immortality refers to the continuation of the cell lineage.

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Large number of offspring produced in the case of

View answer and explanation

Correct option: A

Fertilization that occur in external medium

Option A (Fertilization that occur in external medium) is correct because organisms that undergo external fertilization typically release a large number of gametes to increase the chances of fertilization, as the process is subject to environmental factors and predation.

Solution approach

Correct Answer + Core Reason: Fertilization that occur in external medium. Organisms undergoing external fertilization produce a large number of offspring to increase the chances of fertilization.

Step-by-Step Solution:

Step 1: Understand External Fertilization. External fertilization occurs outside the body, typically in an aquatic environment.

Step 2: Understand Internal Fertilization. Internal fertilization occurs inside the body of the female.

Step 3: Analyze the Need for Large Numbers. In external fertilization, the chances of successful fertilization are lower due to environmental factors, predation, and dilution of gametes. Therefore, a large number of gametes are released to increase the probability of fertilization.

Step 4: Compare to Internal Fertilization. In internal fertilization, the chances of fertilization are higher due to the controlled environment inside the female's body. Therefore, fewer gametes are typically produced.

Why other options are wrong:
- Option B (Fertilization that occur in internal medium): Internal fertilization usually involves fewer offspring due to higher fertilization success rates.
- Option C (Either (a) or (b)): While external fertilization leads to more offspring, internal fertilization generally does not.
- Option D (Both (a) and (b)): External fertilization is more likely to produce a large number of offspring compared to internal fertilization.

Key Concepts:
- External fertilization
- Internal fertilization
- Reproductive strategies
- Offspring number

Memory Aids:
- External = Exposed = More offspring needed.

Quick Tips:
- Remember the differences in reproductive strategies between organisms with external and internal fertilization.

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Which of the correct example of the type of regeneration out of the two major types?

View answer and explanation

Correct option: A

Morphallaxis–regeneration of two transversely cut equal pieces of one Hydra into two small Hydras

Option A (Morphallaxis–regeneration of two transversely cut equal pieces of one Hydra into two small Hydras) is the correct example of morphallaxis because it involves the remodeling of existing tissues to regenerate the whole organism.

Solution approach

Correct Answer + Core Reason: Morphallaxis–regeneration of two transversely cut equal pieces of one Hydra into two small Hydras. Morphallaxis involves remodeling of existing tissues.

Step-by-Step Solution:

Step 1: Define regeneration: The ability of an organism to regrow lost or damaged body parts.

Step 2: Define morphallaxis: A type of regeneration where the entire body is reorganized from a small fragment. There is little or no cell proliferation; instead, existing cells are repurposed.

Step 3: Define epimorphosis: A type of regeneration that involves cell proliferation to replace missing tissues. This is more common in complex organisms.

Step 4: In Hydra, when cut into two pieces, each piece reorganizes its existing cells to form a complete, smaller Hydra. This is morphallaxis.

Step 5: Replacement of old erythrocytes is a normal physiological process, not regeneration.

Step 6: Wound healing is tissue repair, not regeneration of an entire organism.

Step 7: Regeneration of Planaria from crushed pieces is epimorphosis, as it involves significant cell proliferation.

Why other options are wrong:
- Option B: Epimorphosis –replacement of old and dead erythrocytes by the now ones is incorrect because this is a normal physiological process, not regeneration.
- Option C: Morphallaxis-healing of wound in the skin is incorrect because this is tissue repair, not regeneration of an entire organism.
- Option D: Epimorphosis-regeneration of crushed and filtered out pieces of Planaria into as many new planarian is incorrect because regeneration of Planaria from crushed pieces is epimorphosis.

Key Concepts:
- Regeneration
- Morphallaxis
- Epimorphosis

Memory Aids:
- Morphallaxis: Remodeling (Hydra)
- Epimorphosis: Cell proliferation (Limb regeneration)

Quick Tips:
- Distinguish between morphallaxis and epimorphosis based on the mechanism of regeneration.

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The condition in which male and female parts present on the different plant, is called

View answer and explanation

Correct option: D

All of these

Option D (All of these) is correct because heterothallic, dioecious, and unisexual all describe the condition where male and female reproductive parts are present on different plants.

Solution approach

Correct Answer + Core Reason: All of these. Heterothallic, dioecious, and unisexual all describe the condition where male and female parts are on different plants.

Step-by-Step Solution:

Step 1: Define Heterothallic. Heterothallic refers to fungi or algae that require two different thalli (individuals) to complete sexual reproduction.

Step 2: Define Dioecious. Dioecious refers to plants that have male and female reproductive organs on separate individuals.

Step 3: Define Unisexual. Unisexual refers to having either male or female reproductive organs, but not both, on a single individual. In the context of plants, this means separate male and female plants.

Step 4: Relate the Terms. All three terms describe the condition where male and female reproductive parts are not present on the same plant.

Why other options are wrong:
- Option A (Heterothallic): While heterothallic describes this condition in some organisms, it is not the only term.
- Option B (Dioecious): While dioecious describes this condition in plants, it is not the only term.
- Option C (Unisexual): While unisexual describes this condition, it is not the only term.

Key Concepts:
- Heterothallism
- Dioecy
- Unisexuality
- Sexual reproduction

Memory Aids:
- Separate sexes = Hetero/Dio/Uni.

Quick Tips:
- Remember that these terms are used to describe organisms with separate sexes.

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Sugarcane is cultivated through

View answer and explanation

Correct option: A

Stem cutting

Option A (Stem cutting) is correct because sugarcane is typically propagated by planting sections of the stem that contain nodes, which can develop into new plants.

Solution approach

Correct Answer + Core Reason: Stem cutting. Sugarcane is cultivated through stem cuttings, a form of vegetative propagation.

Step-by-Step Solution:

Step 1: Recall the methods of vegetative propagation.

Step 2: Identify stem cutting as a common method for sugarcane.

Step 3: Recognize that stem cuttings contain nodes that can develop into new plants.

Step 4: Conclude that stem cutting is the correct answer.

Why other options are wrong:
- Option B: Root cutting is not the primary method for sugarcane cultivation.
- Option C: True seed is not typically used for sugarcane cultivation due to variability in offspring.
- Option D: Adventitious roots may develop, but the primary method is using stem cuttings with nodes.

Key Concepts:
- Vegetative propagation
- Stem cutting
- Sugarcane cultivation

Memory Aids:
- Think of \"cutting\" a sugarcane stem to plant it.

Quick Tips:
- Consider the practical methods used in agriculture for specific crops.

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Assertion: Endosperm in gymnosperms is haploid as it is formed before fertilization.
Reason: Endosperms is formed post-fertilization in angiosperms and is diploid.

View answer and explanation

Correct option: C

If Assertion is true but Reason is false

Option C (If Assertion is true but Reason is false) is correct because endosperm in gymnosperms is haploid and formed before fertilization, but in angiosperms, it's triploid and formed post-fertilization.

Solution approach

Correct Answer + Core Reason: If Assertion is true but Reason is false. Endosperm in gymnosperms is haploid and pre-fertilization, but in angiosperms, it's triploid and post-fertilization.

Step-by-Step Solution:

Step 1: Analyze the Assertion: Endosperm in gymnosperms is haploid as it is formed before fertilization. This is true. In gymnosperms, the endosperm develops before fertilization and is haploid (n) because it is derived from the female gametophyte.

Step 2: Analyze the Reason: Endosperms is formed post-fertilization in angiosperms and is diploid. This is false. In angiosperms, the endosperm is formed after fertilization and is triploid (3n) due to the fusion of a sperm nucleus with the two polar nuclei in the central cell.

Step 3: Conclusion: The Assertion is true, but the Reason is false.

Why other options are wrong:
- Option A (If both Assertion and Reason are true and Reason is the correct explanation of Assertion): Incorrect because the Reason is false.
- Option B (If both Assertion and Reason are true but Reason is not the correct explanation of Assertion): Incorrect because the Reason is false.
- Option D (If both Assertion and Reason are false): Incorrect because the Assertion is true.

Key Concepts:
- Endosperm Development in Gymnosperms
- Endosperm Development in Angiosperms
- Haploid, Diploid, and Triploid
- Fertilization

Memory Aids:
- Gymnosperm endosperm = haploid, pre-fertilization.
- Angiosperm endosperm = triploid, post-fertilization.

Quick Tips:
- Remember the ploidy level and timing of endosperm development in gymnosperms and angiosperms.

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Self-fertilisation occurs in the

View answer and explanation

Correct option: A

Bisexual flower

Option A (Bisexual flower) is correct because self-fertilization can only occur in flowers that contain both male and female reproductive organs.

Solution approach

Correct Answer + Core Reason: Bisexual flower. Self-fertilization requires both male and female parts in the same flower.

Step-by-Step Solution:

Step 1: Define self-fertilization.

Step 2: Self-fertilization is the fusion of male and female gametes from the same flower.

Step 3: This can only occur if the flower has both male and female reproductive organs (bisexual).

Why other options are wrong:
- Option B: Unisexual flowers have only male or female reproductive organs, preventing self-fertilization.
- Option C: Self-fertilization cannot occur in unisexual flowers.
- Option D: While monoecious plants have both male and female flowers on the same plant, self-fertilization occurs within a single bisexual flower, not between different flowers on the same plant.

Key Concepts:
- Self-fertilization
- Bisexual flower
- Unisexual flower
- Monoecious

Memory Aids:
- Bisexual: Bi- (two) - having both male and female parts.

Quick Tips:
- Remember that self-fertilization requires both male and female parts in the same flower.

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Seasonal breeders are the organisms which reproduces during

View answer and explanation

Correct option: A

Favourable season only

Option A (Favourable season only) is correct because seasonal breeders reproduce only during specific times of the year when environmental conditions are suitable.

Solution approach

Correct Answer + Core Reason: Favourable season only. Seasonal breeders reproduce when conditions are optimal.

Step-by-Step Solution:

Step 1: Define seasonal breeders.

Step 2: Seasonal breeders are organisms that reproduce only during specific seasons.

Step 3: These seasons are typically when environmental conditions are favorable for reproduction and survival of offspring.

Why other options are wrong:
- Option B: Seasonal breeders do not reproduce during unfavorable seasons.
- Option C: Maturation period refers to the time when an organism becomes sexually mature, but seasonal breeders still only reproduce during favorable seasons.
- Option D: Juvenile period is the time before an organism reaches sexual maturity.

Key Concepts:
- Seasonal breeding
- Favorable conditions
- Reproduction

Memory Aids:
- Seasonal: Related to specific seasons.

Quick Tips:
- Think about animals that only reproduce during certain times of the year.

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Single celled animals are said to be immortal because

View answer and explanation

Correct option: D

They continue to live as their daughter cells

Option D is correct because single-celled organisms reproduce by division, and the parent cell ceases to exist as a separate entity, continuing as daughter cells.

Solution approach

Correct Answer + Core Reason: They continue to live as their daughter cells. Single-celled organisms divide, with the parent cell's contents becoming the daughter cells.

Step-by-Step Solution:

Step 1: Understand the concept of immortality in the context of single-celled organisms.

Step 2: Recall that single-celled organisms reproduce asexually through binary fission or similar processes.

Step 3: Recognize that during division, the parent cell divides into daughter cells.

Step 4: Understand that the parent cell essentially ceases to exist as an individual entity, its components becoming part of the daughter cells.

Step 5: Conclude that they are considered immortal because they continue to live as their daughter cells.

Why other options are wrong:
- Option A: They grow indefinitely in size: This is not true; cells have a limited size.
- Option B: They can tolerate any degree of change in temperature: This is not true; cells have temperature limits.
- Option C: They can reproduce throught their life span: While they can reproduce throughout their lifespan, this isn't the reason they are considered immortal. It's about the parent cell continuing as daughter cells.

Key Concepts:
- Asexual reproduction
- Binary fission
- Cellular division
- Concept of immortality in biology

Memory Aids:
- Single-celled immortality: Parent becomes daughter

Quick Tips:
- Focus on the process of cell division and the fate of the parent cell.

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Where does syngamy occur in ……..

View answer and explanation

Correct option: C

Both (a) and (b)

Option C (Both (a) and (b)) is correct because syngamy, the fusion of gametes, can occur in both external and internal mediums depending on the organism.

Solution approach

Correct Answer + Core Reason: Both (a) and (b). Syngamy can occur in both external and internal mediums depending on the organism.

Step-by-Step Solution:

Step 1: Define Syngamy. Syngamy is the fusion of male and female gametes to form a zygote.

Step 2: External Syngamy. In some organisms, such as many aquatic animals and algae, syngamy occurs in the external medium (e.g., water).

Step 3: Internal Syngamy. In other organisms, such as terrestrial plants and animals, syngamy occurs in the internal medium (e.g., inside the female reproductive tract).

Why other options are wrong:
- Option A (External medium): Syngamy can occur in the external medium, but it is not the only possibility.
- Option B (Internal medium): Syngamy can occur in the internal medium, but it is not the only possibility.
- Option D (None of these): Syngamy can occur in both external and internal mediums.

Key Concepts:
- Syngamy
- External fertilization
- Internal fertilization
- Gamete fusion

Memory Aids:
- Syngamy = Fusion (can be inside or outside).

Quick Tips:
- Remember that the location of syngamy depends on the organism's reproductive strategy.

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Arrange the following in ascending manner basing on their lifespan?
(A) Carrot (B) Wolffia (C) Rose (D) Pinus

View answer and explanation

Correct option: D

b,a,c,d

Option D (b,a,c,d) is correct because Wolffia has the shortest lifespan, followed by Carrot, Rose, and then Pinus.

Solution approach

Correct Answer + Core Reason: b,a,c,d. This is the correct ascending order of lifespan.

Step-by-Step Solution:

Step 1: Wolffia (B) has a very short lifespan (few weeks).

Step 2: Carrot (A) is a biennial plant (2 years).

Step 3: Rose (C) is a perennial plant (several years).

Step 4: Pinus (D) is a long-lived perennial tree (many years).

Step 5: Therefore, the ascending order of lifespan is Wolffia < Carrot < Rose < Pinus, or b, a, c, d.

Why other options are wrong:
- Option A: a,b,c,d: Incorrect order, Wolffia has the shortest lifespan.
- Option B: a,b,d,c: Incorrect order, Wolffia has the shortest lifespan and Pinus lives longer than Rose.
- Option C: b,a,d,c: Incorrect order, Pinus lives longer than Rose.

Key Concepts:
- Lifespan
- Plant life cycles (annual, biennial, perennial)

Memory Aids:
- Think of the size and complexity: smaller plants generally have shorter lifespans.

Quick Tips:
- Consider the type of plant (herb, shrub, tree) to estimate lifespan.

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S-I: Reproduction becomes a vital process without which species can survive for long

S-II: Sexual mode of reproduction enables creation of new variants, so that survival advantage is decreased.

View answer and explanation

Correct option: D

Statement I and II are incorrect

Option D (Statement I and II are incorrect) is correct because reproduction is vital for species survival, and sexual reproduction increases survival advantage through variation.

Solution approach

Correct Answer + Core Reason: Statement I and II are incorrect. Reproduction is vital for species survival, and sexual reproduction increases survival advantage.

Step-by-Step Solution:

Step 1: Analyze Statement I: Reproduction becomes a vital process without which species can survive for long. This statement is incorrect. Reproduction *is* vital for the long-term survival of a species. Without reproduction, a species will eventually go extinct.

Step 2: Analyze Statement II: Sexual mode of reproduction enables creation of new variants, so that survival advantage is decreased. This statement is also incorrect. The creation of new variants through sexual reproduction *increases* survival advantage because it allows the species to adapt to changing environments.

Step 3: Conclusion: Both statements are incorrect.

Why other options are wrong:
- Option A (Statement I and II are correct): Incorrect because both statements are false.
- Option B (Statement I is correct and Statement II is incorrect): Incorrect because Statement I is false, and Statement II is also false.
- Option C (Statement I is incorrect and Statement II is correct): Incorrect because Statement I is false, and Statement II is also false.

Key Concepts:
- Importance of Reproduction
- Sexual Reproduction and Variation
- Survival Advantage

Memory Aids:
- Reproduction = species survival.
- Sexual reproduction = increased variation = increased survival advantage.

Quick Tips:
- Consider the long-term implications of reproduction and variation on species survival.

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The sequence of events occurring during the entire lifespan of living organism?

View answer and explanation

Correct option: A

Juvenile phase – mature phase – old age – death

Option A (Juvenile phase – mature phase – old age – death) is correct because it represents the correct sequence of events in the lifespan of a living organism.

Solution approach

Correct Answer + Core Reason: Juvenile phase – mature phase – old age – death. This is the correct sequence of events in an organism's life cycle.

Step-by-Step Solution:

Step 1: The lifespan of an organism starts with a juvenile phase, followed by a mature phase, then old age, and finally death.

Step 2: The juvenile phase is the period of growth and development before reproductive maturity.

Step 3: The mature phase is when the organism is capable of reproduction.

Step 4: Old age is the period of senescence, leading to death.

Why other options are wrong:
- Option B: Mature phase – juvenile phase – old age - death: Incorrect order, mature phase cannot precede juvenile phase.
- Option C: Old age – mature phase – juvenile phase – death: Incorrect order, old age cannot precede juvenile phase.
- Option D: Juvenile phase – old age – mature phase – death: Incorrect order, mature phase must precede old age.

Key Concepts:
- Life cycle stages
- Juvenile phase
- Mature phase
- Senescence

Memory Aids:
- Remember the order: Juvenile -> Mature -> Old Age -> Death (JM-O-D)

Quick Tips:
- Consider the biological processes occurring at each stage to determine the correct order.

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Read the following statements.
1) Statement-A: During favourable conditions, Amoeba undergoes encystation by forming 3 cyst walls.
2) Statement-B: Multiple fission and sporulation occurs in Amoeba under unfavourable conditions.
Choose the correct option.

View answer and explanation

Correct option: D

Only statement B is correct

Option D (Only statement B is correct) is correct because Amoeba undergoes encystation under UNfavorable conditions, and multiple fission/sporulation also occurs under unfavorable conditions.

Solution approach

Correct Answer + Core Reason: Only statement B is correct. Encystation occurs under unfavorable conditions, and multiple fission/sporulation also occurs under unfavorable conditions.

Step-by-Step Solution:

Step 1: Analyze each statement about Amoeba reproduction.

Step 2: Statement A is incorrect: During UNfavorable conditions, Amoeba undergoes encystation by forming 3 cyst walls to protect itself from harsh environments. During favorable conditions, Amoeba reproduces by binary fission.

Step 3: Statement B is correct: Multiple fission and sporulation occur in Amoeba under unfavorable conditions. The cyst divides into many spores, which are released when conditions become favorable.

Step 4: Therefore, only statement B is correct.

Why other options are wrong:
- Option A: Both the statements are correct is incorrect because statement A is false.
- Option B: Both the statements are incorrect is incorrect because statement B is true.
- Option C: Only statement A is correct is incorrect because statement A is false.

Key Concepts:
- Asexual reproduction in Amoeba
- Encystation
- Multiple fission
- Sporulation

Memory Aids:
- Encystation: Unfavorable conditions
- Binary Fission: Favorable conditions

Quick Tips:
- Remember the conditions under which Amoeba undergoes encystation and binary fission.

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Male gametes are also called

View answer and explanation

Correct option: D

Both (1) and (2)

Option D (Both (1) and (2)) is correct because both "antherozoid" and "sperm" are terms used to refer to the male gamete.

Solution approach

Correct Answer + Core Reason: Both (1) and (2). Both antherozoid and sperm are terms used to describe the male gamete.

Step-by-Step Solution:

Step 1: Define male gamete: the reproductive cell in males that fuses with a female gamete during fertilization.

Step 2: Consider the terms "antherozoid" and "sperm".

Step 3: Recognize that both terms refer to the same biological entity, although "antherozoid" is more commonly used in the context of plants and lower animals, while "sperm" is used for animals.

Step 4: Select the option that includes both terms.

Why other options are wrong:
- Option A: Antherozoid is correct but not complete, as "sperm" is also a valid term.
- Option B: Sperm is correct but not complete, as "antherozoid" is also a valid term.
- Option C: Egg is incorrect; it refers to the female gamete.

Key Concepts:
- Gametes
- Male reproductive system
- Terminology in biology

Memory Aids:
- Sperm = Male gamete in animals

Quick Tips:
- Be aware of synonyms in biological terminology.

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Read the following four statements (A-D).

A. The interflowering period in polycarpic plants is not the juvenile phase but is a part of the mature phase.

B. Gametes arise from diploid parent body only.

C. In Chara, egg is rich in proteins and starch only.

D. Reduction division has to occur if a haploid body has to produce haploid gametes.

How many of the above statements is/are correct?

View answer and explanation

Correct option: D

One

Option D (One) is correct because only statement A is correct. The interflowering period is part of the mature phase in polycarpic plants.

Solution approach

Correct Answer + Core Reason: One. Only statement A is correct.

Step-by-Step Solution:

Step 1: Analyze statement A: The interflowering period in polycarpic plants is not the juvenile phase but is a part of the mature phase. This statement is correct. Polycarpic plants flower multiple times, and the period between flowering events is part of their mature, reproductive phase.

Step 2: Analyze statement B: Gametes arise from diploid parent body only. This statement is incorrect. Gametes can arise from both haploid and diploid parent bodies. For example, in bryophytes, the gametophyte is haploid and produces gametes.

Step 3: Analyze statement C: In Chara, egg is rich in proteins and starch only. This statement is incorrect. The egg in Chara is rich in various nutrients, not just proteins and starch.

Step 4: Analyze statement D: Reduction division has to occur if a haploid body has to produce haploid gametes. This statement is incorrect. If a haploid body produces haploid gametes, it does so through mitosis, not reduction division (meiosis).

Step 5: Conclusion: Only statement A is correct.

Why other options are wrong:
- Option A (Two): Incorrect because only one statement is correct.
- Option B (Three): Incorrect because only one statement is correct.
- Option C (Four): Incorrect because only one statement is correct.

Key Concepts:
- Polycarpic Plants
- Juvenile Phase
- Mature Phase
- Gametogenesis
- Reduction Division (Meiosis)
- Mitosis

Memory Aids:
- Polycarpic = many flowering cycles.
- Haploid to haploid = mitosis.

Quick Tips:
- Understand the life cycles of different plants and the processes of gametogenesis.

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The period from birth to natural death is called

View answer and explanation

Correct option: A

Life span

Option A is correct because the life span is defined as the period from birth to natural death of an organism.

Solution approach

Correct Answer + Core Reason: Life span. Life span is the period from birth to natural death.

Step-by-Step Solution:
Step 1: Define the terms:
- Life span: The period from birth to natural death of an organism.
- Life cycle: The series of changes in the life of an organism, including reproduction.
- Life style: The way in which a person lives.
- Reproductive phase: The period when an organism is capable of reproduction.
Step 2: Match the definition with the question.

Why other options are wrong:
- Option B: Life cycle includes all stages of life, not just the period from birth to death.
- Option C: Life style is unrelated to the biological definition.
- Option D: Reproductive phase is only a part of the life span.

Key Concepts:
- Life span
- Life cycle

Memory Aids:
- Span: Length of time

Quick Tips:
- Understand the difference between life span and life cycle.

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