ICAR JRF Plant Science Practice Series Memory Based 2024 (Module 1) (1 – 40 MCQ) 

Question 1

The purine and pyrimidine pairing in DNA is as follows:

1. A—T, G—C
2. A—C, T—G
3. A—T, G—C 
4. A—G, T—C

Correct Answer: 1

Explanation:

• Polyploidy – The condition of having more than two sets of chromosomes.
• Autopolyploid – All chromosome sets come from the same species.
  • Example: Triploid banana (AAA), tetraploid potato (AAAA).
  • Caused by: Failure of meiosis (unreduced gametes) or mitotic doubling.
  • Characteristics: Increased cell size, larger flowers/fruits, but often reduced fertility due to pairing problems.
• Allopolyploid – Chromosome sets come from different species (interspecific hybridization followed by chromosome doubling).
  • Example: Wheat (AABBDD), cotton (AADD), rapeseed (AACC).
• Diploid – Two sets of chromosomes.
• Tetraploid – Four sets (can be auto or allo).

 

 

Question 2

The largest area in India is occupied by the soil group:

1. Black soil
2. Red soil
3. Alluvial soil
4. Lateritic soil

Correct Answer: 3

Explanation:

• Alluvial soil– Covers the largest area in India (about 43% of the total land area). Found in the Indo-Gangetic plains and river deltas.
• Black soil– Found in Deccan Plateau (cotton-growing region).
• Red soil– Found in Tamil Nadu, Karnataka, Andhra Pradesh.
• Lateritic soil– Found in high-rainfall areas (Western Ghats, Northeast).
• Therefore, the correct answer is Alluvial soil→ Option 3.

 

 

Question 3

The cell cycle passes through following stages:

1. G₁ phase → S → G₂ → Division
2. S phase → G₁ → G₂ → Division
3. G₁ phase → G₂ → S → Division
4. G₂ phase → G₁ → S → Division

Correct Answer: 1

Explanation:

• The correct order of the cell cycleis:
  • G₁ phase(Gap 1) – Cell growth, protein synthesis.
  • S phase(Synthesis) – DNA replication.
  • G₂ phase(Gap 2) – Preparation for mitosis.
  • M phase (Division)– Mitosis and cytokinesis.
• Therefore, the correct answer is G₁ phase → S → G₂ → Division→ Option 1.

 

 

Question 4

Biggest organelle of plant cell is:

1. Mitochondria
2. Chloroplast
3. Cytosome
4. Glycosomes

Correct Answer: 2

 

Explanation:

• Chloroplast– The largest organelle in plant cells (up to 10 µm in length). It is the site of photosynthesis.
• Mitochondria– Smaller than chloroplasts (0.5–1 µm).
• Cytosome– Not a standard organelle (refers to the cell body).
• Glycosomes– Small microbodies involved in metabolism.
• Therefore, the correct answer is Chloroplast→ Option 2.

 

 

Question 5

Which one of the following process is called as a necessary evil?

1. Respiration
2. Transpiration
3. Photosynthesis
4. Translocation

Correct Answer: 2

Explanation:

• Transpiration– The loss of water vapor from plant surfaces. It is called a “necessary evil” because it is essential for:
  • Cooling the plant.
  • Creating transpiration pull for water and mineral uptake.
  • However, it also causes water loss, which can be harmful under drought conditions.
• Respiration, photosynthesis, translocation– Not referred to as necessary evil.
• Therefore, the correct answer is Transpiration→ Option 2.

 

 

Question 6

Blossom end rot in tomato is caused by the deficiency of:

1. Ca
2. Mg
3. Mo
4. B

Correct Answer: 1

Explanation:

• Blossom end rot– A physiological disorder in tomato, pepper, and other fruits caused by calcium (Ca) deficiency. Symptoms appear as a dark, sunken lesion at the blossom end of the fruit.
• Mg– Interveinal chlorosis.
• Mo– Whiptail in cauliflower.
• B– Cracked stem, black tip of mango.
• Therefore, the correct answer is Ca→ Option 1.

 

 

Question 7

Intensification of crops in both time and space dimension refers to:

1. Sequential cropping
2. Double cropping
3. Intercropping
4. Monocropping

Correct Answer: 3

Explanation:

• Intercropping– Growing two or more crops simultaneously on the same piece of land. It intensifies cropping in both time and space dimensions.
• Sequential cropping– Growing crops one after another (time dimension only).
• Double cropping– Growing two crops in a year (time dimension only).
• Monocropping– Growing only one crop (no intensification).
• Therefore, the correct answer is Intercropping→ Option 3.

 

 

Question 8

RNA molecule which acts as enzymes are called as:

1. Isozyme
2. Co-enzyme
3. Ribozyme
4. Eponezyme

Correct Answer: 3

Explanation:

• Ribozyme– An RNA molecule that has catalytic activity (acts as an enzyme). Examples include self-splicing introns and ribonuclease P.
• Isozyme– Different forms of the same enzyme (protein).
• Co-enzyme– Organic cofactor that assists enzymes.
• Eponezyme– Not a standard term.
• Therefore, the correct answer is Ribozyme→ Option 3.

 

 

Question 9

Gibberellic acid is sprayed to hybrid rice seed production plots for:

1. Delayed flowering
2. Enhanced flowering
3. To induce flowering
4. Complete exertion of panicle

Correct Answer: 4

Explanation:

• Gibberellic acid (GA₃)– Sprayed on rice panicles to enhance panicle exertion (emergence) from the flag leaf sheath. This is critical in hybrid seed production (especially for CMS lines where panicle exertion is poor).
• Delayed/enhanced/induced flowering– Not the primary purpose.
• Therefore, the correct answer is Complete exertion of panicle→ Option 4.

 

 

Question 10

Energy currency of a cell is:

1. ATP
2. CTP
3. GTP
4. TTP

Correct Answer: 1

Explanation:

• ATP (Adenosine Triphosphate)is universally known as the energy currency of the cell because it stores and transfers chemical energy for cellular processes.
• Hydrolysis of ATP to ADP + Pi releases energy (≈7.3 kcal/mol) used in metabolism, transport, and mechanical work.
• CTP, GTP, TTP– Other nucleotide triphosphates are used in specific processes (e.g., GTP in protein synthesis) but not as the primary energy currency.
• Therefore, the correct answer is ATP→ Option 1.

 

 

Question 11

Chromosomal theory of inheritance was proposed by:

1. Mendel
2. Sutton-Boveri
3. Morgan
4. Darwin

Correct Answer: 2

Explanation:

• The Chromosomal Theory of Inheritancewas independently proposed by Walter Sutton (1902) and Theodor Boveri (1902-1904) .
• They proposed that genes are located on chromosomes and that the behavior of chromosomes during meiosis explains Mendel’s laws.
• Mendel– Discovered the laws of inheritance but did not know about chromosomes.
• Morgan– Worked on linkage and crossing over in Drosophila.
• Darwin– Proposed the theory of evolution.
• Therefore, the correct answer is Sutton-Boveri→ Option 2.

 

 

Question 12

Who coined the term cell?

1. Robert Hooke
2. Stephen Hales
3. Priestley
4. Blackman

Correct Answer: 1

Explanation:

• Robert Hooke (1665)– Observed cork under a compound microscope and coined the term “cell” (Latin cella, meaning small room) because the structures resembled small chambers.
• Stephen Hales– Worked on plant physiology (transpiration, root pressure).
• Priestley– Discovered oxygen and photosynthesis.
• Blackman– Formulated the law of limiting factors.
• Therefore, the correct answer is Robert Hooke→ Option 1.

 

 

Question 13

The eminent feature that differentiates Angiosperm from Gymnosperm seed is:

1. Seed coat
2. Embryo
3. Endosperm
4. Cotyledon

Correct Answer: 3

Explanation:

• Angiosperm seeds– The endosperm is triploid (3n) , formed by double fertilization (fusion of one sperm with two polar nuclei).
• Gymnosperm seeds– The endosperm is haploid (n) , formed from the female gametophyte (pre-fertilization).
• Seed coat, embryo, cotyledons– Present in both groups, not differentiating features.
• Therefore, the correct answer is Endosperm→ Option 3.

 

 

Question 14

The term heterosis was coined by:

1. Shull
2. Johannsen
3. Davenport
4. Morgan

Correct Answer: 1

Explanation:

• Heterosis– The superiority of F₁ hybrids over their parents. The term was coined by George H. Shull (1914).
• Johannsen– Coined the terms “gene,” “genotype,” and “phenotype”.
• Davenport– Proposed the dominance hypothesis of heterosis.
• Morgan– Worked on linkage and crossing over.
• Therefore, the correct answer is Shull→ Option 1.

 

 

Question 15

Stomata found on upper surface of leaf are called as:

1. Hypostomatous
2. Epistomatous
3. Amphistomatous
4. Epicuticular

Correct Answer: 2

Explanation:

• Epistomatous (Epistomatic)– Stomata present only on the upper (adaxial) surface of the leaf.
• Hypostomatous– Stomata present only on the lower (abaxial) surface (most dicots).
• Amphistomatous– Stomata present on both surfaces (many monocots, some dicots).
• Epicuticular– Refers to the wax layer on the leaf surface, not stomata.
• Therefore, the correct answer is Epistomatous→ Option 2.

 

 

Question 16

Green ear symptom of bajra is due to:

1. Rust
2. Ergot
3. Downy mildew
4. Leaf blight

Correct Answer: 3

Explanation:

• Green ear of bajra (pearl millet)is caused by the downy mildew fungus Sclerospora graminicola.
• The inflorescence is transformed into green, leafy structures (phyllody), resembling a “green ear”.
• Rust– Caused by Puccinia (pustules).
• Ergot– Caused by Claviceps (honeydew and sclerotia).
• Leaf blight– Caused by Helminthosporium or Bipolaris.
• Therefore, the correct answer is Downy mildew→ Option 3.

 

 

Question 17

The number of characters selected by Mendel for his study is:

1. 5
2. 10
3. 7
4. 22

Correct Answer: 3

Explanation:

• Mendel studied 7 charactersin pea (Pisum sativum):
  1. Seed shape (round/wrinkled)
  2. Seed colour (yellow/green)
  3. Flower colour (purple/white)
  4. Pod shape (inflated/constricted)
  5. Pod colour (green/yellow)
  6. Flower position (axial/terminal)
  7. Stem height (tall/dwarf)
• Therefore, the correct answer is 7→ Option 3.

 

 

Question 18

Which of the following is only minimally absorbed by chlorophylls a and b?

1. Violet light
2. Green light
3. Blue light
4. Red light

Correct Answer: 2

Explanation:

• Chlorophylls a and babsorb light most strongly in the blue (430-450 nm) and red (640-680 nm)
• Green light (500-600 nm)is minimally absorbed and is mostly reflected, which is why plants appear green.
• Violet light– Absorbed moderately.
• Therefore, the correct answer is Green light→ Option 2.

 

 

Question 19

White bud of maize is due to:

1. Mg
2. Zn
3. Ca
4. Fe

Correct Answer: 2

Explanation:

• White bud of maizeis caused by zinc (Zn) deficiency.
• Symptoms: Young leaves become pale yellow to white (bleached), especially near the base; internodes shorten; plants may die.
• Mg– Interveinal chlorosis in older leaves.
• Ca– Death of growing points, leaf tip burn.
• Fe– Interveinal chlorosis in young leaves.
• Therefore, the correct answer is Zn→ Option 2.

 

 

Question 20

Plant virus containing DNA is:

1. Potato mosaic virus
2. Tobacco mosaic virus
3. Cauliflower mosaic virus
4. Papaya ring spot virus

Correct Answer: 3

Explanation:

• Cauliflower mosaic virus (CaMV)– A dsDNA (double-stranded DNA) virus, belonging to the family Caulimoviridae.
• Potato mosaic virus, Tobacco mosaic virus (TMV), Papaya ring spot virus– All have ssRNA
• Therefore, the correct answer is Cauliflower mosaic virus→ Option 3.

 

 

Question 21

The modern technique for varietal identification is:

1. Electrophoresis
2. Grow-out test
3. Phenol test
4. Polysaccharide

Correct Answer: 1

Explanation:

• Electrophoresis– A modern, rapid, and reliable technique for varietal identification based on protein or DNA banding patterns.
• Grow-out test– Traditional field test for genetic purity (time-consuming).
• Phenol test– Chemical test for seed colour reaction (limited to certain crops).
• Polysaccharide– Not a varietal identification technique.
• Therefore, the correct answer is Electrophoresis→ Option 1.

 

 

Question 22

Light reactions of photosynthesis take place in:

1. Cristae
2. Cytoplasm
3. Mitochondria
4. Thylakoids

Correct Answer: 4

Explanation:

• Light reactions(light-dependent reactions) of photosynthesis occur in the thylakoid membranes of chloroplasts (containing chlorophyll and other pigments).
• Cristae– Inner mitochondrial membrane.
• Cytoplasm– Site of glycolysis.
• Mitochondria– Site of cellular respiration.
• Therefore, the correct answer is Thylakoids→ Option 4.

 

 

Question 23

Noble cane is:

1. Saccharum officinarum
2. Saccharum robustum
3. Saccharum sinense
4. Saccharum spontaneum

Correct Answer: 1

Explanation:

• Noble cane– Refers to Saccharum officinarum, which has thick stems, high sugar content, and is the primary cultivated sugarcane species.
• robustum– A wild relative, thick but low sugar.
• sinense– Thin, hardy, used in some regions.
• spontaneum– Wild, thin, low sugar, used in breeding for hardiness.
• Therefore, the correct answer is Saccharum officinarum→ Option 1.

 

 

Question 24

The enzyme responsible for prediction of viability through Tetrazolium test is:

1. Peroxidase
2. Amylase
3. Super oxide dismutase
4. Dehydrogenase

Correct Answer: 4

Explanation:

• Tetrazolium test (TZ test)– A seed viability test that uses 2,3,5-triphenyl tetrazolium chloride.
• The test is based on the activity of dehydrogenase enzymesin living tissues. Dehydrogenases reduce the colorless tetrazolium salt to red formazan.
• Peroxidase, amylase, superoxide dismutase– Not detected by TZ test.
• Therefore, the correct answer is Dehydrogenase→ Option 4.

 

 

Question 25

An Alloaugamous oilseed is:

1. Safflower
2. Groundnut
3. Sesame
4. Mustard

Correct Answer: 1

Explanation:

• Alloaugamous– A plant that is cross-pollinated (allogamous). Among oilseeds, safflower is cross-pollinated (pollinated by insects).
• Groundnut, sesame, mustard– Primarily self-pollinated (autogamous).
• Therefore, the correct answer is Safflower→ Option 1.

 

 

Question 26

The ecological suicide of the crop seeds occur at field due to accumulation of:

1. HCN
2. Ethylene
3. Carbon monoxide
4. Carbon disulphide

Correct Answer: 1

Explanation:

• Ecological suicide– Germination of seeds in the field under unfavorable conditions (e.g., after rainfall) followed by desiccation, leading to death.
• In some crops (e.g., sorghum), seeds can accumulate HCN (hydrogen cyanide), which can cause toxicity. However, “ecological suicide” often refers to premature germination (vivipary) or seed death.
• Given the options, HCNis associated with seed toxicity.
• Therefore, the correct answer is HCN→ Option 1.

 

 

Question 27

The element which is involved in energy transfer and storage in plants is:

1. N
2. P
3. K
4. Ca

Correct Answer: 2

Explanation:

• Phosphorus (P)– A key component of ATP (energy currency) , NADPH, and other energy-transfer molecules. It is also part of nucleic acids and phospholipids.
• N– Component of proteins, nucleic acids.
• K– Osmotic regulation, enzyme activation.
• Ca– Cell wall structure, signaling.
• Therefore, the correct answer is P→ Option 2.

 

 

Question 28

Synaptonemal complex appears during:

1. Leptotene
2. Zygotene
3. Diakinesis
4. Diplotene

Correct Answer: 2

Explanation:

• Synaptonemal complex– A protein structure that forms between homologous chromosomes during synapsis.
• It appears during zygotene(the stage of prophase I where homologous chromosomes begin to pair).
• Leptotene– Chromosomes condense; no pairing.
• Diakinesis– Terminalization of chiasmata.
• Diplotene– Chiasmata visible, homologous chromosomes begin to separate.
• Therefore, the correct answer is Zygotene→ Option 2.

 

 

Question 29

The second generation Bt cotton contains genes of:

1. Cry 1 Ac, Cry 2 Ab
2. Cry 2 Ac, 2 Ab
3. Cry 2 Ac, Cry 1 Ab
4. Cry 1 Ac, 1 Ab

Correct Answer: 1

Explanation:

• First generation Bt cotton– Contained a single gene, Cry 1 Ac (active against bollworms).
• Second generation Bt cotton– Contains two genes: Cry 1 Ac and Cry 2 Ab (or Cry 1 Ac and Cry 2 Ab) for better insect resistance and to delay resistance development.
• Therefore, the correct answer is Cry 1 Ac, Cry 2 Ab→ Option 1.

 

 

Question 30

Masanobu Fukuoka is the pioneer of:

1. Conservation farming
2. Organic farming
3. Natural farming
4. Chemical farming

Correct Answer: 3

Explanation:

• Masanobu Fukuoka (1913-2008)– A Japanese farmer and philosopher, known as the pioneer of “Natural Farming” (do-nothing farming) .
• His method emphasizes no tillage, no fertilizers, no pesticides, and no weeding (as much as possible).
• Conservation farming– Focuses on soil conservation.
• Organic farming– Avoids synthetic inputs but may use tillage.
• Chemical farming– Conventional agriculture.
• Therefore, the correct answer is Natural farming→ Option 3.

 

 

Question 31

Azure blue colour tag is enclosed with the seed bag of:

1. Certified seed
2. Foundation seed
3. Breeder seed
4. Nucleus seed

Correct Answer: 3

Explanation:

• In the Indian seed certification system:
  • Breeder seed– Azure blue
  • Foundation seed– White tag.
  • Certified seed– Golden brown (or blue for some crops).
  • Nucleus seed– No tag.
• Therefore, the correct answer is Breeder seed→ Option 3.

 

 

Question 32

The enzyme involved in transcription is:

1. RNA polymerase
2. Taq polymerase
3. DNA polymerase I
4. DNA polymerase III

Correct Answer: 1

Explanation:

• Transcription– The process of synthesizing RNA from a DNA template. It is catalyzed by RNA polymerase.
• Taq polymerase– Used in PCR (DNA amplification).
• DNA polymerase I and III– Involved in DNA replication.
• Therefore, the correct answer is RNA polymerase→ Option 1.

 

 

Question 33

The highest % N is present in:

1. Urea
2. Ammonium nitrate
3. Urea sulphate
4. Anhydrous ammonia

Correct Answer: 4

Explanation:

• Anhydrous ammonia (NH₃)– Contains 82% N (highest among nitrogenous fertilizers).
• Urea (CO(NH₂)₂)– Contains 46% N.
• Ammonium nitrate (NH₄NO₃)– Contains 33-35% N.
• Urea sulphate– Lower N content (around 30-35%).
• Therefore, the correct answer is Anhydrous ammonia→ Option 4.

 

 

Question 34

Seed Act was formulated and enacted during:

1. 1966 and 1968
2. 1966 and 1969
3. 1963 and 1966
4. 1988 and 1990

Correct Answer: 1

Explanation:

• The Seeds Act, 1966was passed by the Indian Parliament in 1966 and came into force in 1968.
• It regulates the quality of seeds sold in India and establishes the Central Seed Certification Board.
• Therefore, the correct answer is 1966 and 1968→ Option 1.

 

 

Question 35

The total number of codons are:

1. 60
2. 62
3. 64
4. 66

Correct Answer: 3

Explanation:

• The genetic code consists of 64 codons(triplet combinations of four nucleotides: 4³ = 64).
• Out of these, 61 codonscode for amino acids, and 3 codons are stop codons (UAA, UAG, UGA).
• Therefore, the correct answer is 64→ Option 3.

 

 

Question 36

Which state leads in acreage and productivity of Indian mustard?

1. Rajasthan
2. Madhya Pradesh
3. Punjab
4. Uttar Pradesh

Correct Answer: 1

Explanation:

• Rajasthanis the leading state in India in terms of both acreage and productivity of Indian mustard (Brassica juncea).
• The state accounts for nearly 50% of the total mustard area in India.
• Madhya Pradesh, Punjab, Uttar Pradesh– Also produce mustard but less than Rajasthan.
• Therefore, the correct answer is Rajasthan→ Option 1.

 

 

Question 37

An example for slow releasing N fertilizer is:

1. S coated urea
2. AM
3. N serve
4. PSB

Correct Answer: 1

Explanation:

• S coated urea (Sulfur-coated urea)– A slow-release nitrogen fertilizer. The sulfur coating gradually breaks down, releasing urea slowly over time.
• AM– Not a standard slow-release fertilizer.
• N serve (Nitrapyrin)– A nitrification inhibitor, not a slow-release fertilizer.
• PSB (Phosphate Solubilizing Bacteria)– Biofertilizer for phosphorus.
• Therefore, the correct answer is S coated urea→ Option 1.

 

 

Question 38

During DNA replication, the enzyme which separates the two sides of the helix is called as:

1. DNA polymerase
2. DNA amylase
3. DNA ligase
4. DNA helicase

Correct Answer: 4

Explanation:

• DNA helicase– The enzyme that unwinds and separates the two strands of the DNA double helix by breaking hydrogen bonds between base pairs.
• DNA polymerase– Synthesizes new DNA strands.
• DNA ligase– Joins Okazaki fragments.
• DNA amylase– Not a real enzyme (amylase breaks down starch).
• Therefore, the correct answer is DNA helicase→ Option 4.

 

 

Question 39

The Electron Microscope was invented by:

1. Knoll and Ruska
2. Clark and Adams
3. Watson and Crick
4. Robert Koch

Correct Answer: 1

Explanation:

• The electron microscopewas invented by Ernst Ruska and Max Knoll in 1931.
• Ruskareceived the Nobel Prize in Physics in 1986 for this invention.
• Watson and Crick– Discovered DNA double helix.
• Robert Koch– Developed Koch’s postulates.
• Therefore, the correct answer is Knoll and Ruska→ Option 1.

 

 

Question 40

Barbara McClintock was awarded Nobel Prize in 1984 for the discovery of:

1. Split genes
2. Pseudo genes
3. Jumping genes
4. Overlapping genes

Correct Answer: 3

Explanation:

• Barbara McClintockdiscovered transposable elements (jumping genes) in maize (corn) in the 1940s-1950s.
• She was awarded the Nobel Prize in Physiology or Medicine in 1983(not 1984; the question has a typo).
• Split genes– Discovered by Richard Roberts and Phillip Sharp (Nobel 1993).
• Pseudo genes– Non-functional copies of genes.
• Overlapping genes– Genes that share nucleotide sequences.
• Therefore, the correct answer is Jumping genes→ Option 3.