Free Biological Molecules MCQs with Answers
1,790 Biological Molecules MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
The chapter covers water's polarity and biological roles, carbohydrates, lipids, proteins and nucleic acids, including their monomers, bonds, structures and functions. It also distinguishes RNA from DNA and explains conjugated molecules such as glycoproteins, glycolipids and nucleoproteins, which combine organic molecules with a non-protein component.
Last updated
1,790 questions · page 13 of 90
- A. Magnesium
- B. Nitrogen
- C. Potassium
- D. Phosphorus
Explanation: Nitrogen deficiency reduces chlorophyll formation, producing widespread or strong yellowing called chlorosis, especially in older leaves.
Correct answer: Nitrogen- A. Organic
- B. Inorganic
- C. Wet
- D. Terrestrial
Explanation: Autotrophs use inorganic raw materials such as carbon dioxide, water and mineral salts to manufacture organic food, usually using light or…
Correct answer: Inorganic- A. Plant
- B. Fungus
- C. Animal
- D. Algae
Explanation: Puccinia is a parasitic fungus that obtains nutrients from living plant tissues and causes rust diseases.
Correct answer: Fungus- A. Stunted growth & strong chlorosis
- B. No electron transport chains
- C. Premature death of leaves
- D. Stunted growth of roots
Explanation: Potassium regulates enzyme activity, osmotic balance and movement of materials in plants; its deficiency can cause marginal leaf damage…
Correct answer: Premature death of leaves- A. Cytochromes
- B. ATP
- C. Chlorophyll
- D. Haemoglobin
Explanation: Magnesium is the central mineral ion in the chlorophyll molecule and is essential for capturing light energy during photosynthesis.
Correct answer: Chlorophyll- A. Metabolic processes of an organism
- B. Providing energy
- C. Formation of sturctures
- D. All of these
Explanation: Carbohydrates and fats supply energy, proteins provide amino acids for growth and repair, and all three classes contribute to metabolic…
Correct answer: All of these- A. Prokaryotae
- B. Plantae
- C. Monera
- D. Protista
Explanation: Amoeba is a unicellular eukaryote classified in Kingdom Protista because it has a true nucleus and lacks the specialized organization of…
Correct answer: Protista- A. Phylum
- B. Family
- C. Genus
- D. Order
Explanation: A genus groups closely related species and therefore generally contains organisms with more similarities than a broader rank such as…
Correct answer: Genus- A. Nitrobacter
- B. Nitrosomonas
- C. Rhizohium
- D. All of these
Explanation: Nitrification is the conversion of ammonia into nitrite and then nitrate, carried out mainly by Nitrosomonas and Nitrobacter.
Correct answer: Rhizohium- A. Autotroph
- B. Heterotroph
- C. Parasite
- D. Saprophyte
Explanation: Consumers cannot manufacture organic food from inorganic substances, so they obtain nutrients by feeding on other organisms or their…
Correct answer: Heterotroph- A. Autotrophs
- B. Heterotrophs
- C. Procariotique
- D. Eu-cariotique
Explanation: Autotrophs make organic food from inorganic substances such as carbon dioxide and water, using light energy or chemical energy, and store…
Correct answer: Autotrophs- A. H
- B. N & O
- C. P & S
- D. All of these
Explanation: Carbon forms stable covalent bonds with hydrogen, nitrogen, oxygen, phosphorus and sulfur, allowing the construction of diverse biological…
Correct answer: All of these- A. Humus
- B. Detritus
- C. Dead microscopic animals
- D. Small crustaceans
Explanation: Hydra is a carnivorous freshwater animal that captures prey with its tentacles and stinging cells.
Correct answer: Small crustaceans- A. Sponges
- B. Annelida
- C. Platyhelminthes
- D. Aves
Explanation: Platyhelminthes are triploblastic because they develop from three germ layers, and acoelomate because they lack a fluid-filled body cavity…
Correct answer: Platyhelminthes- A. Chordate
- B. Protochordate
- C. Lower chordate
- D. All of these
Explanation: Amphioxus, or Branchiostoma, has chordate features such as a notochord, dorsal hollow nerve cord and pharyngeal slits.
Correct answer: All of these- A. Algae
- B. Bacteria
- C. Cyanobacteria
- D. Chlamydomonas
Explanation: Cyanobacteria are among the simplest organisms that perform oxygenic photosynthesis, using light energy to split water and releasing…
Correct answer: Cyanobacteria- A. Amoebas
- B. Zooflagellates
- C. Ciliates
- D. Apicomplexans
Explanation: Apicomplexans are generally non-motile in their mature stages and lack the usual locomotory structures such as cilia, flagella or…
Correct answer: Apicomplexans- A. 20
- B. 25
- C. 150
- D. 170
Explanation: Although 20 amino acids are commonly used to build proteins, about 170 amino acids have been identified in cells and tissues, including…
Correct answer: 170- A. H
- B. CH3
- C. COOH
- D. C = O
Explanation: Glycine is the simplest amino acid because its side, or R, group is a hydrogen atom, giving it the structure NH2-CH2-COOH.
Correct answer: H- A. Sori - Indusium
- B. Arthrophytes - Jointed
- C. Dichotomous - Vernation
- D. Lycopods - Ground pries
Explanation: Sori are clusters of fern sporangia and may be covered by an indusium, arthrophytes have jointed or segmented stems, and lycopods are…
Correct answer: Dichotomous - Vernation