All Free Biology MCQs with Answers

1671. Carbohydrates, fats & proteins are essential for_______________?

• 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 processes and body structures. Therefore all listed functions are included. Students may choose providing energy because it is the most familiar function, but it does not include the structural and metabolic roles.

1672. Amoeba belongs to which kingdom______________?

• 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 plants, animals or fungi. Prokaryotae and Monera refer to prokaryotic organisms without a membrane-bound nucleus. Students may choose c because Amoeba is microscopic, but microscopic size does not make an organism a moneran.

1673. Animals with greatest number of similarities are grouped together in a/an___________?

• 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 family, order or phylum. For example, members of Homo share more characteristics than all members of the family Hominidae. Students may choose b because a family also contains related organisms, but it includes several genera and is less specific than genus.

1674. All of the following are involved in nitrification except

• 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. Rhizobium fixes atmospheric nitrogen in legume root nodules rather than carrying out nitrification. The likely alternative is d, but 'all of these' is incorrect because Rhizobium is excluded.

1675. What is the characteristic feature of consumers?

• 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 products and are therefore heterotrophs. Parasites and saprophytes are specific types of heterotrophs, not the defining feature of every consumer. Students may choose parasite by treating one feeding method as the general definition.

1676. Those organisms which can prepare their own food from simple inorganic material and can store energy are called___________?

• 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 that energy in chemical bonds. Heterotrophs must obtain ready-made organic food from other organisms. Students may choose heterotrophs if they focus on energy storage without considering how the food is produced.

1677. Carbon commonly combines with______________?

• 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 molecules. These elements occur in carbohydrates, lipids, proteins, nucleic acids and other organic compounds. Students may choose only H or N and O by recalling one biomolecule class, but carbon commonly combines with all the listed elements.

1678. The food of hydra consists of___________?

• 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. Its food commonly includes small crustaceans and other small aquatic animals, which are then digested in its gastrovascular cavity. Students may choose c because Hydra can eat microscopic animals, but the standard option describing its usual prey here is small crustaceans.

1679. Which of the following are triploblastic and acoelomate?

• 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 between the gut and body wall. Sponges do not have true germ layers, while annelids and birds are coelomate animals. Students may choose b by remembering that annelids are triploblastic but overlooking that they possess a true coelom.

1680. Amphoixus is a__________?

• 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. It is therefore a protochordate and is commonly called a lower chordate, making all three descriptions applicable. Students may choose b or c by selecting only one classification level instead of recognizing that the terms overlap.