✈ AFCAT General Awareness20 Questions · No Negative Marking
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Question 1 of 20
The "powerhouse of the cell" is the:
Mitochondria produce ATP (energy currency) through cellular respiration. They have their own DNA and are semi-autonomous. They are most numerous in cells with high energy demand like muscle and liver cells.
Question 2 of 20
Which organelle is called the "suicidal bag" of the cell?
Lysosomes contain ~40 digestive (hydrolytic) enzymes. They digest worn-out organelles and foreign material. If ruptured, these enzymes digest the cell itself — hence "suicidal bag." Formed by the Golgi apparatus.
Question 3 of 20
In DNA, adenine (A) always pairs with:
In DNA: A pairs with T (2 hydrogen bonds); G pairs with C (3 hydrogen bonds). Uracil replaces Thymine only in RNA. This complementary base pairing was confirmed by Watson and Crick in 1953.
Question 4 of 20
Mitosis produces:
Mitosis (equational division) produces 2 daughter cells with the same chromosome number as the parent (diploid, 2n). It is used for growth, repair, and asexual reproduction. Meiosis produces 4 haploid cells (n) — gametes.
Question 5 of 20
Which organelle is called the "post office of the cell"?
The Golgi apparatus (Golgi body) receives proteins from the endoplasmic reticulum, modifies, packages, and dispatches them to their destination inside or outside the cell — like a postal sorting office.
Question 6 of 20
The double helix structure of DNA was discovered by:
James Watson and Francis Crick proposed the double helix model of DNA in 1953, based in part on X-ray crystallography data by Rosalind Franklin. They received the Nobel Prize in Physiology or Medicine in 1962.
Question 7 of 20
In a monohybrid cross (Tt × Tt), the phenotypic ratio of tall to dwarf plants is:
Monohybrid cross Tt × Tt gives genotypes TT : 2Tt : tt = 1:2:1 (genotypic ratio). Both TT and Tt are tall (T is dominant), so phenotypic ratio = 3 Tall : 1 Dwarf. The 9:3:3:1 ratio is for dihybrid cross.
Question 8 of 20
Prokaryotic cells differ from eukaryotic cells because they:
Prokaryotes (bacteria, blue-green algae) have no membrane-bound nucleus. Their DNA lies freely in the cytoplasm in a region called the nucleoid. They have 70S ribosomes (not 80S). Examples: bacteria, Mycoplasma.
Question 9 of 20
Which organelle is responsible for protein synthesis?
Ribosomes are the sites of protein synthesis (translation of mRNA into polypeptide chains). Called the "protein factory." They are non-membrane bound and present in both prokaryotes (70S) and eukaryotes (80S).
Question 10 of 20
Meiosis is essential for the formation of:
Meiosis (reductional division) produces gametes (sperm/egg) with half the chromosome number (haploid, n). When sperm and egg unite, the diploid number (2n) is restored. In humans: 2n=46 → gametes with n=23.
Question 11 of 20
How many hydrogen bonds link Guanine (G) and Cytosine (C) in a DNA double helix?
G–C pairs are held by 3 hydrogen bonds; A–T pairs are held by 2 hydrogen bonds. Therefore DNA with higher G–C content is more thermally stable and harder to denature (separate the strands).
Question 12 of 20
Chloroplasts are found only in:
Chloroplasts are found only in plant cells and photosynthetic algae. They contain chlorophyll and perform photosynthesis. Like mitochondria, they have double membranes and their own DNA (semi-autonomous).
Question 13 of 20
Which is the correct sequence of the central dogma of molecular biology?
The central dogma: DNA (transcription) → mRNA (translation) → Protein. Transcription occurs in the nucleus; translation occurs at ribosomes. Proposed by Francis Crick in 1958.
Question 14 of 20
The total number of chromosomes in a normal human body cell is:
Normal human somatic (body) cells are diploid (2n=46), having 23 pairs of chromosomes (22 autosomes + 1 sex chromosome pair). Gametes (sperm/egg) are haploid with only 23 chromosomes.
Question 15 of 20
Which of the following is NOT a membrane-bound organelle?
Ribosomes have NO membrane. They are made of RNA and protein. All other organelles listed — mitochondria, lysosome, Golgi — are membrane-bound. Ribosomes are present in both prokaryotes and eukaryotes.
Question 16 of 20
What is the genotypic ratio in Mendel's monohybrid cross (Tt × Tt)?
Crossing over during meiosis is significant because it:
Crossing over during meiosis I (prophase I) exchanges DNA segments between homologous chromosomes, creating new gene combinations. This genetic recombination is the main source of genetic variation in sexually reproducing organisms.
Question 18 of 20
The cell wall of bacteria is composed of:
Bacterial cell walls are made of peptidoglycan (murein). Plant cell walls are made of cellulose; fungal cell walls of chitin; lignin provides rigidity to woody plants. This distinction is important for antibiotic action (e.g., penicillin disrupts peptidoglycan synthesis).
Question 19 of 20
The "Father of Genetics" is:
Gregor Mendel (1822–1884), an Austrian monk, conducted pea plant hybridisation experiments and formulated the laws of inheritance. His work was rediscovered in 1900. Robert Hooke discovered the cell (1665); Darwin proposed evolution.
Question 20 of 20
Which RNA carries the genetic message from DNA in the nucleus to the ribosome for protein synthesis?
mRNA (messenger RNA) is transcribed from DNA in the nucleus and carries the genetic code (codons) to ribosomes in the cytoplasm. tRNA brings amino acids to the ribosome; rRNA is a structural component of the ribosome itself.