All Free Biology MCQs with Answers

1661. Penicillium reproduce via___________?

• A. Spores
• B. Conidia
• C. Budding
• D. Fragmentation

Explanation: Penicillium reproduces asexually by producing conidia, which are nonmotile spores formed externally on brush-like conidiophores. The broader answer spores may seem correct, but conidia is the specific type of spore produced by Penicillium.

1662. Root like structure in saprotrophic fungi are called_______________?

• A. Rhizodis
• B. Haustoria
• C. Hyphae
• D. Constricting rings

Explanation: Rhizoids are root-like hyphal structures that anchor saprotrophic fungi and help absorb nutrients from the substrate; option a is evidently intended to spell rhizoids. Haustoria are specialized absorptive structures of parasitic fungi that penetrate a living host, so choosing them confuses saprotrophy with parasitism.

1663. Nodules on roots of leguminous plants have __________ bacteria?

• A. Anaerobic
• B. Nitrogen fixing
• C. Nitrifying
• D. Ammonifying

Explanation: Root nodules of leguminous plants contain Rhizobium, which converts atmospheric nitrogen into usable nitrogen compounds through nitrogen fixation. Nitrifying bacteria convert ammonia or nitrites into other nitrogen compounds but do not form the characteristic symbiosis in these nodules. Students may choose nitrifying bacteria because both processes belong to the nitrogen cycle.

1664. Puccinia commonly destroys______________?

• A. Corn
• B. Tomato
• C. Dodder
• D. Wheat

Explanation: Puccinia is the rust fungus responsible for diseases such as wheat rust, which damages wheat plants and reduces yield. Corn is affected by other fungal diseases, so students may choose corn by confusing rust with common corn smut or rust diseases.

1665. Stunted growth of roots is due to the deficiency of____________in plants?

• A. Potassium
• B. Magnesium
• C. Phosphorus
• D. Iron.

Explanation: Phosphorus is needed for ATP, nucleic acids and membrane phospholipids, and its deficiency particularly restricts root growth and development. Potassium deficiency more commonly causes poor growth and leaf symptoms, so students may choose potassium because it is also a major plant macronutrient.

1666. Strong chlorosis is due to the deficiency of _____________ in plants?

• 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. Magnesium and iron deficiencies can also cause chlorosis, so students may choose magnesium because magnesium is part of chlorophyll or iron because iron is needed for chlorophyll formation.

1667. Autotrophic organisms can exist in an exclusively ________________ environment?

• 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 chemical energy. Therefore they can exist in an exclusively inorganic environment, although they still require suitable physical conditions. Students may choose wet because many autotrophs need water, but water alone does not describe their nutritional source.

1668. Puccinia is a parasitic___________?

• 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. It is not a plant, animal or alga, although its growth on plants may lead students to classify it as a plant.

1669. Deficiency of K+ causes_____________?

• 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 followed by premature death of leaves. Stunted root growth is more characteristically associated with phosphorus deficiency, so students may choose option d by confusing the two mineral-deficiency symptoms.

1670. Magnesium is present in which of the following__________________?

• 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. Haemoglobin contains iron, while cytochromes contain iron and ATP contains phosphate groups, so students may choose haemoglobin by confusing the central metal ions of chlorophyll and haemoglobin.