All Free Biology MCQs with Answers

• A. Lysosomes
• B. Ribosomes
• C. Cisternae
• D. Golgi body

Explanation: Factual recall; Option A mentions lysosomes, which contain hydrolytic enzymes that digest old organelles or phagocytosed particles. Option B mentions ribosomes; messenger RNA (mRNA) is decoded in a ribosome, outside the nucleus, to produce a specific amino acid chain or polypeptide. Option C, cisternae, describes the sac-like tubules that make up the endoplasmic reticulum. Option D, Golgi body, is involved in packaging of already synthesized proteins and their subsequent transport or secretion.

• A. 750 um
• B. 50 um
• C. 500 um
• D. 250 um

Explanation: Recall the formula for magnification, where Image Size (I)= Actual Size (A) x Magnification (M), or I=A x M. The magnification is the product of the eyepiece lens and objective lens' respective magnifications so; M= 5 x 10 = 50. The question asks for the size of the image so; I=A x M = 15 x 50 = 750 um.

• A. Lysosome
• B. Nucleus
• C. Nucleosome
• D. Mitochondria

Explanation: Chloroplasts and mitochondria are the two organelles, that contain circular DNA similar, to those found in prokaryotic cells, along with 70S ribosomes, which are also similar to the ones in prokaryotes, such as in bacteria. This can be traced back to the endosymbiotic theory, where mitochondria and chloroplasts are understood to be ancient prokaryotes.

• A. RNA
• B. DNA
• C. Nucleus
• D. Eukaryotic ribosomes

Explanation: Ribosomes are called the ribonucleoprotein particles in a cell. They are called so because they are formed by the association of both RNA and protein. They may be suspended freely in the cytoplasm or transiently attached to the walls of the endoplasmic reticulum as they get the signal from the nucleus.

• A. Lack of a cytoplast
• B. Presence of a cell wall
• C. Inability to create proton gradients
• D. mRNA translation simultaneous to transcription

Explanation: Prokaryotes are unicellular organisms that lack membrane-bound structures, including the nucleus, which is the hub of 'Transcription'. This makes it improbable for 'Translation' and 'Transcription' to occur simultaneously.

• A. Golgi complex
• B. Lysosomes
• C. Peroxisomes
• D. Glyoxysomes

Explanation: Lysosomes function as the digestive system of the cell, serving both to degrade material taken up from outside the cell and to digest obsolete components of the cell itself.

• A. Nucleosome
• B. Nucleus
• C. Chromosomes
• D. Histones

Explanation: Nucleosomes are the basic packing unit of DNA built from histone proteins around which DNA is coiled. Nucleosomes are connected by short DNA segments (termed 'linker DNA') into nucleosomal arrays, which undergo short-range interactions with neighbouring nucleosomes to form chromatin fibres. Subsequent fibre-fibre interactions contribute to the high degree of compaction observed in the condensed chromosome. They serve as a scaffold for formation of higher order chromatin structure as well as for a layer of regulatory control of gene expressio.

• A. Microfilaments
• B. Microvilli
• C. Microtubules
• D. Intermediate filaments

Explanation: Typical centrioles are made of 9 triplets of microtubules organized with radial symmetry.

• A. Proteins and carbohydrates
• B. RNA and lipid
• C. RNA and proteins
• D. RNA and carbohydrates

Explanation: A ribosome is an intercellular structure made up of equal amounts of both RNA and protein, hence named as 'ribonucleo-protein particles 'and it is the site of protein synthesis in the cell. The ribosome reads the messenger RNA (mRNA) sequence and translates that genetic code into a specified string of amino acids, which grow into long chains that fold to form proteins.

• A. A and B
• B. B and C
• C. A and C
• D. A and D

Explanation: ATP synthesis is seen in both chloroplasts and mitochondria. The inner membrane of mitochondria is folded to increase surface area. Both mitochondria and chloroplasts have small, circular DNA, all kinds of RNA and 70S ribosomes. Oxidative phosphorylation takes place only in mitochondria.