CUET UG Categorised PYQ Biology Unit 1 -

📚

CUET UG Categorised PYQ Biology Unit 1

BIOLOGY

⏱️ 30 Minutes

❓ 27 Questions

📅 2022, 2023, 2024 & 2025

✍️ Long Answers

📌 Answers are locked once submitted — results and explanations appear at the end.

CUET UG Categorised PYQ Biology Unit 1

1 / 27

QUESTION 1 OF 27

Types of cells in 2 celled pollen grains are ______. (PYQ 2022 Shift 1)

Answer Review

1 Types of cells in 2 celled pollen grains are ______. (PYQ 2022 Shift 1)

A Central cell and Synergids

B Antipodals and Megaspore

C Micropylar and Filiform

D Vegetative and Generative

💡 Short Explanation

Mature pollen grain usually has two cells. Vegetative cell forms pollen tube. Generative cell forms male gametes.

✅ Correct Answer Explanation

At shedding, most angiosperm pollen grains are two-celled. They contain a large vegetative cell and a smaller generative cell. The generative cell later divides to produce two male gametes.

❓ Why Other Options Are Incorrect

Option A) Components of embryo sac.
Option B) Female reproductive structures.
Option C) Not pollen cell types.

🎯 Strategy

Used: NCERT Recall

Option A → Embryo sac.
Option B → Female structures.
Option C → Incorrect terms.
Option D → Correct.

Final Answer → Vegetative and Generative.

🧠 Memory Trick

📚 → Section/Theme: Pollen Grain

2 What will be the number of chromosomes in the gamete of maize if its meiocyte contains 20 chromosomes? (PYQ 2023 Shift 1)

A 10

B 20

C 24

D 40

💡 Short Explanation

Meiocyte is diploid (2n). Gametes are haploid (n). Meiosis reduces chromosome number by half.

✅ Correct Answer Explanation

Meiocytes undergo meiosis to produce gametes. During meiosis, the chromosome number is reduced from diploid (2n) to haploid (n). Since the meiocyte of maize contains 20 chromosomes (2n = 20), the resulting gametes will contain 10 chromosomes (n = 10).

❓ Why Other Options Are Incorrect

Option B) 20 → Represents diploid chromosome number, not gametic number.
Option C) 24 → Not related to chromosome reduction from 20.
Option D) 40 → Chromosome number cannot double during gamete formation.

🎯 Strategy

Used: Dimensional/Unit Analysis

Option A → Half of diploid number.
Option B → Original diploid count.
Option C → Arbitrary value.
Option D → Opposite of meiosis outcome.

Final Answer → Meiosis halves chromosome number.

🧠 Memory Trick

📚 → Section/Theme: Microsporogenesis and Meiosis

3 Which layer of microsporangium nourishes the developing pollen grains? (PYQ 2023 Shift 1)

A Epidermis

B Endothecium

C Middle layer

D Tapetum

💡 Short Explanation

Innermost wall layer. Rich in nutrients. Feeds developing microspores.

✅ Correct Answer Explanation

Tapetum is the innermost layer of the microsporangium wall. It supplies nourishment and essential materials required for pollen grain development. It is metabolically active and often multinucleate.

❓ Why Other Options Are Incorrect

Option A) Epidermis → Protective outer layer.
Option B) Endothecium → Helps anther dehiscence.
Option C) Middle layer → Temporary supporting layer.

🎯 Strategy

Used: Elimination

Option A → Protection.
Option B → Dehiscence.
Option C → Support.
Option D → Nutrition.

Final Answer → Tapetum nourishes pollen grains.

🧠 Memory Trick

📚 → Section/Theme: Structure of Anther

4 Match the following: (PYQ 2023 Shift 1)

List I	List II
A. Albuminous seed	I. Groundnut
B. Parthenocarpic fruit	II. Apple
C. Non-albuminous seed	III. Castor
D. False fruit	IV. Banana

A (A)–(I), (B)–(IV), (C)–(III), (D)–(II)

B (A)–(III), (B)–(IV), (C)–(I), (D)–(II)

C (A)–(II), (B)–(I), (C)–(IV), (D)–(III)

D (A)–(IV), (B)–(III), (C)–(II), (D)–(I)

💡 Short Explanation

Castor → Albuminous seed. Banana → Parthenocarpic fruit. Groundnut → Non-albuminous seed. Apple → False fruit.

✅ Correct Answer Explanation

Albuminous seed retains endosperm (Castor). Non-albuminous seeds consume endosperm during development (Groundnut). Banana develops without fertilization and is parthenocarpic. Apple is a false fruit because the thalamus contributes to fruit formation.

❓ Why Other Options Are Incorrect

Option A → Incorrect matching of albuminous and false fruit.
Option C → Multiple incorrect associations.
Option D → Albuminous and parthenocarpic fruit mismatched.

🎯 Strategy

Used: Option Grouping

Option A → Partial mismatch.
Option B → All correct matches.
Option C → Multiple errors.
Option D → Multiple errors.

Final Answer → Only Option B satisfies all pairs.

🧠 Memory Trick

📚 → Section/Theme: Fruits and Seeds

5 Maximum number of male gametes produced from one pollen mother cell (microspore mother cell) will be : (PYQ 2023 Shift 2)

A Two

B Four

C Eight

D Sixteen

💡 Short Explanation

One PMC forms four microspores. Each pollen grain forms two male gametes. Total = 4 × 2 = 8.

✅ Correct Answer Explanation

One pollen mother cell undergoes meiosis to produce four microspores. Each microspore develops into a pollen grain that ultimately produces two male gametes. Therefore, maximum male gametes = 4 × 2 = 8.

❓ Why Other Options Are Incorrect

Option A) Too few.
Option B) Counts only microspores.
Option D) Exceeds biological limit.

🎯 Strategy

Used: Substitution

Option A → Incorrect.
Option B → Microspore count only.
Option C → Correct calculation.
Option D → Excessive value.

Final Answer → Eight.

🧠 Memory Trick

📚 → Section/Theme: Microsporogenesis

📄 Passage

The following diagram shows an endospermic seed of Maize grain. Answer the following question:

'X' developed from which part of angiospermic plant ? (PYQ 2023 Shift 2)

A Ovary cell

B Zygote

C Sepals

D Petals

💡 Short Explanation

X represents embryo. Embryo develops after fertilization. Formed from zygote.

✅ Correct Answer Explanation

The embryo of a seed develops from the zygote formed after fertilization. In maize grain, the embryonal axis and associated structures originate from the zygote.

❓ Why Other Options Are Incorrect

Option A) Ovary cell → Forms fruit wall.
Option C) Sepals → Floral accessory parts.
Option D) Petals → Floral accessory parts.

🎯 Strategy

Used: NCERT Recall

Option A → Fruit formation.
Option B → Embryo origin.
Option C → Floral whorl.
Option D → Floral whorl.

Final Answer → Zygote.

🧠 Memory Trick

📚 → Section/Theme: Embryo Development

📄 Passage

The following diagram shows an endospermic seed of Maize grain. Answer the following question:

The part which provides nourishment to the developing embryo is : (PYQ 2023 Shift 2)

A A

B Y

C B

D D

💡 Short Explanation

Y represents endosperm. Endosperm stores food. Nourishes developing embryo.

✅ Correct Answer Explanation

Maize is an endospermic seed. The endosperm persists in the mature seed and serves as the major food reserve supplying nutrients to the developing embryo.

❓ Why Other Options Are Incorrect

Option A) A → Embryonic structure.
Option C) B → Protective sheath.
Option D) D → Embryonic part.

🎯 Strategy

Used: Diagram Identification

Option A → Not storage tissue.
Option B → Endosperm.
Option C → Protective structure.
Option D → Embryonic structure.

Final Answer → Y.

🧠 Memory Trick

📚 → Section/Theme: Structure of Monocot Seed

📄 Passage

The following diagram shows an endospermic seed of Maize grain. Answer the following question:

In diagram the sheath which covers radicle is shown by ? (PYQ 2023 Shift 2)

A A

B B

C C

D D

💡 Short Explanation

Radicle covering = Coleorhiza. Protective sheath. Characteristic of monocot seeds.

✅ Correct Answer Explanation

In maize grain, the radicle is enclosed within a protective sheath called coleorhiza. This structure protects the radicle during seed germination.

❓ Why Other Options Are Incorrect

Option A) Not coleorhiza.
Option C) Usually represents plumule sheath.
Option D) Other embryonic structure.

🎯 Strategy

Used: NCERT Recall

Option A → Incorrect.
Option B → Coleorhiza.
Option C → Coleoptile.
Option D → Embryonic part.

Final Answer → B.

🧠 Memory Trick

📚 → Section/Theme: Monocot Seed Structure

📄 Passage

The following diagram shows an endospermic seed of Maize grain. Answer the following question:

In the diagram the scutellum is represented by: (PYQ 2023 Shift 2)

A A

B Y

C Z

D D

💡 Short Explanation

Scutellum is the cotyledon of maize. Located between embryo and endosperm. Absorbs food from endosperm.

✅ Correct Answer Explanation

The scutellum is the single cotyledon present in monocot seeds such as maize. It absorbs nutrients from the endosperm and transfers them to the embryo.

❓ Why Other Options Are Incorrect

Option A) Different embryonic structure.
Option B) Endosperm.
Option D) Protective sheath.

🎯 Strategy

Used: Diagram Identification

Option A → Not cotyledon.
Option B → Endosperm.
Option C → Scutellum.
Option D → Protective structure.

Final Answer → Z.

🧠 Memory Trick

📚 → Section/Theme: Structure of Maize Seed

📄 Passage

The following diagram shows an endospermic seed of Maize grain. Answer the following question:

In diagram the sheath which covers plumule is shown by: (PYQ 2023 Shift 2)

A A

B B

C C

D D

💡 Short Explanation

Plumule covering = Coleoptile. Protects shoot apex. Characteristic monocot structure.

✅ Correct Answer Explanation

In monocot seeds such as maize, the plumule is enclosed by a protective sheath called coleoptile. It protects the young shoot during germination.

❓ Why Other Options Are Incorrect

Option A) Not coleoptile.
Option B) Coleorhiza surrounds radicle.
Option D) Other embryonic structure.

🎯 Strategy

Used: NCERT Recall

Option A → Incorrect.
Option B → Radicle sheath.
Option C → Coleoptile.
Option D → Other structure.

Final Answer → C.

🧠 Memory Trick

📚 → Section/Theme: Monocot Seed Structure

11 In artificial hybridisation bagging is done to: (PYQ 2023 Shift 3)

A Remove anthers

B Prevent unnecessary fruit formation

C Ensure cross pollination

D Prevent contamination of stigma with unwanted pollen

💡 Short Explanation

Bagging follows emasculation. Protects stigma. Prevents unwanted pollen deposition.

✅ Correct Answer Explanation

In artificial hybridisation, the emasculated flower is covered with a bag to prevent contamination of the stigma by unwanted pollen grains. This ensures controlled pollination with desired pollen.

❓ Why Other Options Are Incorrect

Option A) Removal of anthers is emasculation.
Option B) Not the purpose of bagging.
Option C) Bagging prevents contamination, not pollination itself.

🎯 Strategy

Used: NCERT Recall

Option A → Emasculation.
Option B → Incorrect.
Option C → Indirect effect.
Option D → Correct.

Final Answer → Option D.

🧠 Memory Trick

📚 → Section/Theme: Artificial Hybridisation

12 Match List I with List II (PYQ 2023 Shift 3)

List I	List II
A. Attaches ovule to the placenta	I. Hilum
B. Region where ovule fuses with its stalk	II. Chalaza
C. Place where integuments are not present	III. Funicle
D. Basal part of ovule	IV. Micropyle

A A–III, B–I, C–IV, D–II

B A–III, B–IV, C–I, D–II

C A–III, B–II, C–I, D–IV

D A–II, B–IV, C–I, D–III

💡 Short Explanation

Funicle attaches ovule to placenta. Hilum is fusion point. Micropyle lacks integuments. Chalaza is basal region.

✅ Correct Answer Explanation

Funicle connects ovule to placenta. Hilum is the junction where ovule fuses with stalk. Micropyle is the opening left by integuments. Chalaza is the basal part opposite the micropyle.

❓ Why Other Options Are Incorrect

Option B) Hilum and micropyle mismatched.
Option C) Chalaza incorrectly matched.
Option D) Multiple mismatches.

🎯 Strategy

Used: Option Grouping

Option A → Correct.
Option B → Incorrect.
Option C → Incorrect.
Option D → Incorrect.

Final Answer → Option A.

🧠 Memory Trick

📚 → Section/Theme: Structure of Ovule

13 Observe the given diagram and answer the questions given below:
Question: The method of embryo sac formation from a single megaspore is termed ______ development. (PYQ 2023 Shift 3)

A Tetrasporic

B Monosporic

C Polysporic

D Bisporic

💡 Short Explanation

One megaspore remains functional. Embryo sac develops from it. Most common type in angiosperms.

✅ Correct Answer Explanation

In most flowering plants, only one megaspore remains functional and develops into the embryo sac. Such development is called monosporic development.

❓ Why Other Options Are Incorrect

Option A) Embryo sac develops from four nuclei.
Option C) Not a standard embryo sac type.
Option D) Embryo sac develops from two nuclei.

🎯 Strategy

Used: NCERT Recall

Option A → Tetrasporic.
Option B → Correct.
Option C → Incorrect.
Option D → Bisporic.

Final Answer → Monosporic.

🧠 Memory Trick

📚 → Section/Theme: Female Gametophyte Development

14 Observe the given diagram and answer the questions given below:
Question: Identify the correct statements with respect to female gametophyte. (PYQ 2023 Shift 3)
Choose the correct answer from the options given below:

A A, D only

B A and B only

C B, C and D only

D A, B and C only

💡 Short Explanation

Egg apparatus occurs at micropylar end. Female gametophyte = embryo sac. MMC undergoes meiosis.

✅ Correct Answer Explanation

Statement A is incorrect because the egg apparatus is present at the micropylar end. Statements B, C and D are correct according to the standard Polygonum type embryo sac development.

❓ Why Other Options Are Incorrect

Option A) Includes incorrect statement A.
Option B) Includes incorrect statement A.
Option D) Includes incorrect statement A.

🎯 Strategy

Used: Elimination

Option A → A incorrect.
Option B → A incorrect.
Option C → Correct.
Option D → A incorrect.

Final Answer → Option C.

🧠 Memory Trick

📚 → Section/Theme: Embryo Sac Structure

15 Observe the given diagram and answer the questions given below:
Question: Match the following: (PYQ 2023 Shift 3)

List I	List II
A. Nucellus	I. G
B. Megaspore dyad	II. B
C. Micropylar end	III. D
D. Megaspore mother cell	IV. C

A A-I, B-IV, C-II, D-III

B A-II, B-I, C-IV, D-III

C A-III, B-IV, C-I, D-II

D A-IV, B-III, C-I, D-II

💡 Short Explanation

Nucellus surrounds MMC. Dyad forms after first meiotic division. Micropylar end contains micropyle.

✅ Correct Answer Explanation

Based on the standard NCERT megasporogenesis diagram: Nucellus → G Megaspore dyad → C Micropylar end → B Megaspore mother cell → D Hence Option A is correct.

❓ Why Other Options Are Incorrect

Option B) Nucellus incorrectly matched.
Option C) Multiple mismatches.
Option D) Incorrect diagram labels.

🎯 Strategy

Used: Diagram Identification

Option A → Correct.
Option B → Incorrect.
Option C → Incorrect.
Option D → Incorrect.

Final Answer → Option A.

🧠 Memory Trick

📚 → Section/Theme: Megasporogenesis

16 Observe the given diagram and answer the questions given below:
Question: Which part of the ovule differentiates a large cell with dense cytoplasm and a prominent nucleus during megasporogenesis? (PYQ 2023 Shift 3)

A Micropylar region of the nucellus

B Chalazal region of the nucellus

C Centre of the nucellus

D Inner integument

💡 Short Explanation

Archesporial cell develops here. Gives rise to MMC. Initiates megasporogenesis.

✅ Correct Answer Explanation

A hypodermal cell in the micropylar region of the nucellus enlarges, develops dense cytoplasm and a prominent nucleus, and differentiates into the archesporial cell, which ultimately forms the megaspore mother cell.

❓ Why Other Options Are Incorrect

Option B) Not the site of archesporial differentiation.
Option C) Not specified in NCERT.
Option D) Does not form MMC.

🎯 Strategy

Used: NCERT Recall

Option A → Correct.
Option B → Incorrect.
Option C → Incorrect.
Option D → Incorrect.

Final Answer → Option A.

🧠 Memory Trick

📚 → Section/Theme: Megasporogenesis

17 Observe the given diagram and answer the questions given below:
Question: How many mitotic divisions occur in the nucleus of the functional megaspore to form embryo sac? (PYQ 2023 Shift 3)

A Two

B Five

C Four

D Three

💡 Short Explanation

Functional megaspore is haploid. Undergoes three mitotic divisions. Produces eight nuclei.

✅ Correct Answer Explanation

The functional megaspore undergoes three successive mitotic divisions: 1 → 2 nuclei 2 → 4 nuclei 4 → 8 nuclei This results in the typical eight-nucleate embryo sac.

❓ Why Other Options Are Incorrect

Option A) Produces only four nuclei.
Option B) Excessive divisions.
Option C) Produces sixteen nuclei.

🎯 Strategy

Used: Substitution

Option A → Too few.
Option B → Too many.
Option C → Produces 16 nuclei.
Option D → Produces 8 nuclei.

Final Answer → Three.

🧠 Memory Trick

📚 → Section/Theme: Female Gametophyte Development

18 In a velvet grass seed, the cotyledon is called : (PYQ 2024 Shift 1, 2024 Shift 2)

A Scutellum

B Coleorrhiza

C Coleoptile

D Testa

💡 Short Explanation

Grass seeds are monocot seeds. Monocot cotyledon is called scutellum. Helps absorb nutrients from endosperm.

✅ Correct Answer Explanation

In monocotyledonous seeds such as grasses, the single cotyledon is called the scutellum. It lies between the embryo and endosperm and absorbs nutrients from the endosperm during germination for transfer to the growing embryo.

❓ Why Other Options Are Incorrect

Option B → Coleorrhiza is the protective sheath covering the radicle.
Option C → Coleoptile is the protective sheath covering the plumule.
Option D → Testa is the seed coat.

🎯 Strategy

Used: Odd One Out

Option A → Cotyledon structure.
Option B → Radicle covering.
Option C → Plumule covering.
Option D → Seed coat.

Final Answer → Only scutellum is the cotyledon.

🧠 Memory Trick

📚 → Class 11 Biology, NCERT, Chapter 2: Sexual Reproduction in Flowering Plants, Structure of Monocot Seed.

19 Which one of the following is not associated with megasporangium ? (PYQ 2024 Shift 1)

A Funicle

B Integument

C Generative cell

D Micropyle

💡 Short Explanation

Megasporangium refers to ovule. Funicle, integument and micropyle are ovule parts. Generative cell belongs to pollen grain.

✅ Correct Answer Explanation

The megasporangium (ovule) consists of nucellus, integuments, micropyle and funicle. The generative cell is a component of the male gametophyte (pollen grain) and is not associated with the ovule.

❓ Why Other Options Are Incorrect

Option A → Funicle attaches ovule to placenta.
Option B → Integuments surround the nucellus.
Option D → Micropyle is the opening in ovule.

🎯 Strategy

Used: Odd One Out

Option A → Ovule structure.
Option B → Ovule structure.
Option C → Male gametophyte structure.
Option D → Ovule structure.

Final Answer → Generative cell.

🧠 Memory Trick

📚 → Class 12 Biology, Chapter 2: Sexual Reproduction in Flowering Plants.

20 In diploid organisms, which of the following undergoes meiosis? (PYQ 2024 Shift 1)

A Vegetative cell

B Sporogenous tissue

C Pollen grain

D Synergids

💡 Short Explanation

Meiosis forms haploid spores. Sporogenous tissue is diploid. Pollen grains and synergids are already haploid.

✅ Correct Answer Explanation

The diploid sporogenous tissue inside microsporangia undergoes meiosis to produce haploid microspores. These later develop into pollen grains.

❓ Why Other Options Are Incorrect

Option A → Does not undergo meiosis.
Option C → Product of meiosis.
Option D → Haploid female gametophyte cell.

🎯 Strategy

Used: Elimination

Option A → No meiosis.
Option B → Undergoes meiosis.
Option C → Produced after meiosis.
Option D → Haploid cell.

Final Answer → Sporogenous tissue.

🧠 Memory Trick

📚 → Class 12 Biology, Chapter 2: Sexual Reproduction in Flowering Plants.

21 Which one of the following guides the entry of the pollen tube into the embryo sac? (PYQ 2025 Shift 1)

A Antipodal cells

B Filiform apparatus

C Micropyle

D Synergids

💡 Short Explanation

Present in synergid cells. Guides pollen tube towards egg apparatus. Helps in pollen tube reception.

✅ Correct Answer Explanation

The filiform apparatus is a specialized structure present at the micropylar end of synergid cells. It plays a crucial role in attracting and guiding the pollen tube into the embryo sac. After reaching the embryo sac, the pollen tube enters one synergid through the filiform apparatus and releases the male gametes. Thus, the filiform apparatus acts as the guiding structure during fertilization in angiosperms.

❓ Why Other Options Are Incorrect

A) Antipodal cells
Located at the chalazal end and mainly provide nourishment. They do not guide the pollen tube.
C) Micropyle
It is the opening through which the pollen tube enters the ovule, but it does not actively guide it.
D) Synergids
Synergids help in pollen tube reception, but the specific guiding structure within them is the filiform apparatus.

🎯 Strategy

Used: Elimination

Option A → Located at opposite end of embryo sac.
Option B → Known guiding structure.
Option C → Only an opening.

Final Answer → Based on elimination.

🧠 Memory Trick

"Filiform = File the pollen tube in the right direction."

📚 Class 12 Biology – Chapter 2: Sexual Reproduction in Flowering Plants – Embryo Sac and Fertilization

22 Which one of the following is opposite part of micropylar end of ovule? (PYQ 2025 Shift 1)

A Hilum

B Chalaza

C Funicle

D Nucellus

💡 Short Explanation

Micropyle at one end. Chalaza at opposite end. Characteristic ovule structure.

✅ Correct Answer Explanation

The chalaza is the basal region of the ovule opposite to the micropylar end. It is the area where integuments and nucellus merge. The embryo sac is situated between the micropylar and chalazal ends.

❓ Why Other Options Are Incorrect

A) Hilum
Attachment point of ovule.
C) Funicle
Stalk connecting ovule and placenta.
D) Nucellus
Nutritive tissue of ovule.

🎯 Strategy

Used: NCERT Recall

Option A → Attachment region.
Option B → Opposite of micropyle.
Option C → Connecting stalk.

Final Answer → Based on NCERT recall.

🧠 Memory Trick

Micro ↔ Chalaza (Opposite Ends)

📚 Class 12 Biology – Chapter 2: Sexual Reproduction in Flowering Plants – Structure of Ovule

📄 Passage

Read the passage carefully and answer the questions based on the passage:
Pollen pistil interaction involves all events from the landing of pollen grains on the stigma until the pollen tube enters the embryo sac (when the pollen is compatible). When a pollen tube grows through the style and enters into the ovules, it finally discharges two male gametes in one of the synergids. Syngamy and triple fusion are two fusion events occur in angiosperms. Thus, angiosperms exhibit double fertilization. The products of these fusions are the diploid zygote and triploid primary endosperm nucleus. Zygote develops into embryo and primary endosperm cell forms the endosperm tissue. The developing embryo passes through different stages before maturation.

Question:
With reference to reproduction in flowering plants, which one of the following is incorrect? (PYQ 2025 Shift 1)

A Endosperm develops into seed

B Ovary develops into fruit

C Fusion of polar nuclei

D Syngamy is fusion of male and female gamete

💡 Short Explanation

Seed develops from ovule. Endosperm provides nourishment. Endosperm does not become the seed.

✅ Correct Answer Explanation

After fertilization, the ovule develops into a seed while the ovary develops into a fruit. Endosperm is a nutritive tissue formed from the primary endosperm nucleus and supplies nutrients to the developing embryo. Therefore, the statement that endosperm develops into seed is incorrect.

❓ Why Other Options Are Incorrect

B) Ovary develops into fruit
Correct statement.
C) Fusion of polar nuclei
Occurs during triple fusion.
D) Syngamy is fusion of male and female gamete
Correct definition of syngamy.

🎯 Strategy

Used: Elimination

Option A → Incorrect developmental pathway.
Option B → Correct post-fertilization event.
Option C → Correct reproductive process.

Final Answer → Based on elimination.

🧠 Memory Trick

Ovule → Seed, Ovary → Fruit

📚 Class 12 Biology, Chapter 2 – Sexual Reproduction in Flowering Plants, Post-Fertilization Events

📄 Passage

Question:
Which of the following is not a stage of growing embryo in dicotyledon plants? (PYQ 2025 Shift 1)

A Heart-shaped

B Globular

C Pre-embryo

D Bird

💡 Short Explanation

Dicot embryo passes through globular stage. Heart-shaped stage follows. Bird is not an embryonic stage.

✅ Correct Answer Explanation

Development of a dicot embryo proceeds through stages such as proembryo (pre-embryo), globular embryo, heart-shaped embryo, and mature embryo. "Bird" is not a recognized developmental stage in plant embryology. Hence it is the incorrect option.

❓ Why Other Options Are Incorrect

A) Heart-shaped
A valid dicot embryo stage.
B) Globular
An early embryonic stage.
C) Pre-embryo
Occurs before later embryo differentiation.

🎯 Strategy

Used: Odd One Out

Option A → Embryonic stage.
Option B → Embryonic stage.
Option C → Embryonic stage.

Final Answer → Based on odd one out.

🧠 Memory Trick

Globular → Heart-shaped → Mature

📚 Class 12 Biology, Chapter 2 – Sexual Reproduction in Flowering Plants, Embryogenesis

📄 Passage

Question:
The coconut water from tender coconut, a good source of nutrition is nothing but: (PYQ 2025 Shift 1)

A Free nuclear endosperm

B Synergids

C Antipodal cells

D Scutellum

💡 Short Explanation

Coconut water is liquid endosperm. Rich in nutrients. Formed by free nuclear divisions.

✅ Correct Answer Explanation

In coconut, the liquid found inside tender fruits is free nuclear endosperm. During development, nuclei divide repeatedly without immediate cell wall formation, creating a multinucleate liquid tissue. This liquid later contributes to the nutritive endosperm of the seed.

❓ Why Other Options Are Incorrect

B) Synergids
Cells associated with the egg apparatus.
C) Antipodal cells
Located at the chalazal end of embryo sac.
D) Scutellum
Cotyledon of monocot embryo.

🎯 Strategy

Used: NCERT Recall

Option A → Standard NCERT example.
Option B → Embryo sac cell.
Option C → Embryo sac cell.

Final Answer → Based on NCERT recall.

🧠 Memory Trick

Tender Coconut Water = Liquid Endosperm

📚 Class 12 Biology, Chapter 2 – Sexual Reproduction in Flowering Plants, Endosperm Development

📄 Passage

Question:
Formation of diploid zygote is a result of: (PYQ 2025 Shift 1)

A Emasculation

B Triple fusion

C Syngamy

D Bagging

💡 Short Explanation

Male and female gametes fuse. Diploid zygote is formed. Fundamental fertilization event.

✅ Correct Answer Explanation

Syngamy is the fusion of one male gamete with the egg cell. This fusion restores the diploid chromosome number and forms the zygote. Triple fusion forms the primary endosperm nucleus and does not produce the zygote.

❓ Why Other Options Are Incorrect

A) Emasculation
Removal of anthers during artificial hybridization.
B) Triple fusion
Forms primary endosperm nucleus.
D) Bagging
Prevents unwanted pollination.

🎯 Strategy

Used: NCERT Recall

Option A → Hybridization technique.
Option B → Endosperm formation.
Option C → Zygote formation.

Final Answer → Based on fertilization process.

🧠 Memory Trick

Syngamy = Sperm + Egg

📚 Class 12 Biology, Chapter 2 – Sexual Reproduction in Flowering Plants, Double Fertilization

📄 Passage

Question:
If there are 38 chromosomes in the zygote, how many chromosomes will be there in its haploid egg cell? (PYQ 2025 Shift 1)

A 38

B 57

C 19

D 76

💡 Short Explanation

Zygote is diploid (2n). Egg cell is haploid (n). Haploid number is half of diploid number.

✅ Correct Answer Explanation

A zygote is formed by the fusion of two haploid gametes and therefore contains the diploid chromosome number (2n). If the zygote contains 38 chromosomes, the haploid number is 19. Thus, the egg cell contributing to the zygote would contain 19 chromosomes.

❓ Why Other Options Are Incorrect

A) 38
Represents diploid number, not haploid.
B) 57
Not related to chromosome reduction.
D) 76
Represents chromosome doubling beyond diploid level.

🎯 Strategy

Used: Substitution

Option A → Diploid count.
Option B → Incorrect calculation.
Option C → 38 ÷ 2 = 19.

Final Answer → Based on chromosome number reduction.

🧠 Memory Trick

Gamete = Half of Zygote

📚 Class 12 Biology, Chapter 2 – Sexual Reproduction in Flowering Plants, Fertilization and Ploidy

CUET UG Categorised PYQ Biology Unit 1

Test Complete!

Answer Review