2026 IJMB Biology Questions and Answers

This page provides well-structured, exam-focused answers for key 2026 IJMB Biology questions. Use the short versions for quick revision and the extended versions to strengthen your explanations in the exam.

NUMBER TWO

(2a) Lichens

Version I (Short Answer)

Lichens are composite organisms formed by a symbiotic association between a fungus and an alga or cyanobacterium. The fungal partner provides protection, water, and minerals, while the algal partner carries out photosynthesis and supplies food. Lichens commonly grow on rocks, tree bark, and walls and are important indicators of air quality.

Version II (Extended Answer)

Lichens are composite organisms formed from a mutualistic relationship between a fungus, usually an ascomycete, and a photosynthetic partner, which is either green algae or cyanobacteria. The fungal partner is called the mycobiont and it provides structure, protection, and absorbs water and minerals. The algal partner is the phycobiont and it carries out photosynthesis, supplying food to both. Lichens grow on rocks, tree bark, and bare soil. They are pioneer species in ecological succession and very sensitive to air pollution, especially sulphur dioxide, so they serve as bioindicators of air quality. Reproduction is mainly vegetative through soredia or fragmentation.

(2b) Air Pollution

Version I (Short Answer)

Air pollution is the contamination of the atmosphere by harmful substances, including smoke, dust, gases, and industrial emissions. Major sources include vehicle exhausts, factory emissions, bush burning, and fossil fuel combustion. Air pollution can cause respiratory diseases, damage plants and animals, and contribute to global warming and acid rain.

Version II (Extended Answer)

Air pollution is the presence of harmful substances in the atmosphere in quantities that cause damage to living organisms and the environment. Major pollutants include carbon monoxide from incomplete combustion, sulphur dioxide from industries, nitrogen oxides from vehicle exhaust, particulate matter, and chlorofluorocarbons. Sources are mainly industrial emissions, burning of fossil fuels, bush burning, and vehicle exhaust. Effects include respiratory diseases like asthma and bronchitis, acid rain which damages plants and buildings, depletion of the ozone layer, and global warming due to greenhouse gases. Control measures include using filters in factories, catalytic converters in vehicles, afforestation, and enacting and enforcing pollution control laws.

(2c) Heterospory

Version I (Short Answer)

Heterospory is the production of two different types of spores by the same plant, namely microspores (male spores) and megaspores (female spores). This condition occurs in some pteridophytes and seed plants. Heterospory represents an important evolutionary step toward the development of seeds and the emergence of separate male and female gametophytes.

Version II (Extended Answer)

Heterospory is the production of two different types of spores by a plant species. These are microspores, which are small and develop into male gametophytes, and megaspores, which are large and develop into female gametophytes. It is common in Selaginella, Salvinia, and all seed plants. Heterospory is considered an important step in the evolution of seed habit in plants. It ensures cross fertilization, leads to better survival of the female gametophyte because it is retained and nourished within the megasporangium, and reduces dependence on water for fertilization. It is an advancement over homospory where only one type of spore is produced.

(2d) Asexual Reproduction

Version I (Short Answer)

Asexual reproduction is a mode of reproduction in which offspring are produced from a single parent without the fusion of gametes. The offspring are genetically identical to the parent. Common methods include binary fission, budding, fragmentation, spore formation, and vegetative propagation. It allows rapid multiplication and colonization of suitable environments.

Version II (Extended Answer)

Asexual reproduction is a type of reproduction that involves only one parent and does not involve the fusion of gametes. Offspring produced are genetically identical to the parent and are called clones. Methods include binary fission in Amoeba, budding in yeast and Hydra, fragmentation in Spirogyra, spore formation in Rhizopus, and vegetative propagation in plants using stems, roots, or leaves. Advantages are that it is rapid, requires less energy, produces many offspring in a short time, and good traits are preserved. Disadvantages include lack of genetic variation, so offspring are vulnerable to the same diseases and cannot adapt easily to environmental changes.

NUMBER THREE

Economic Importance of Bacteria

• Decomposition of Organic Matter: Bacteria play a vital role as decomposers by breaking down dead plants, animals, and organic wastes into simpler substances. This process recycles nutrients back into the soil, improves soil fertility, and maintains ecological balance.
• Nitrogen Fixation and Soil Fertility: Certain bacteria such as Rhizobium convert atmospheric nitrogen into forms that plants can absorb and utilize. This enriches the soil with nitrogen compounds, promotes plant growth, and increases agricultural productivity.
• Food Production and Fermentation: Bacteria are used in the production of various foods through fermentation. For example, Lactobacillus is used in making yoghurt, cheese, and other dairy products. Fermentation improves food preservation, taste, and nutritional value.
• Industrial and Pharmaceutical Uses: Bacteria are employed in the manufacture of antibiotics, enzymes, vitamins, and organic acids. Antibiotics such as streptomycin and tetracycline are produced by bacterial species and are widely used in medicine to treat diseases.
• Sewage Treatment and Waste Management: Bacteria help in the decomposition of sewage and organic wastes in treatment plants. They break down harmful substances, reduce pollution, and make waste disposal safer for the environment.
• Biotechnology and Genetic Engineering: Bacteria are widely used in scientific research and biotechnology. They serve as hosts for recombinant DNA technology, enabling the production of insulin, vaccines, growth hormones, and other useful biological products.
• Bioremediation and Environmental Protection: Some bacteria can degrade toxic chemicals, oil spills, pesticides, and other pollutants. This process, known as bioremediation, helps to clean contaminated soil and water, thereby protecting the environment and public health.

NUMBER FIVE

(5a) Potato Blight

Potato blight is a serious plant disease that affects potatoes and is caused by a fungus-like organism known as Phytophthora infestans. It spreads rapidly under cool and wet conditions, attacking leaves, stems, and tubers. The disease causes dark patches on leaves which later rot and collapse, leading to a significant reduction in crop yield. In severe cases, it can destroy an entire potato farm if not properly controlled. Control measures include the use of resistant varieties, proper field hygiene, crop rotation, and application of fungicides.

(5b) Climate Change

Climate change is the long-term alteration in the average weather conditions of the Earth, such as temperature, rainfall, and wind patterns. It is mainly caused by increased concentrations of greenhouse gases like carbon dioxide and methane due to human activities such as burning fossil fuels, deforestation, and industrial processes. Climate change leads to effects such as rising global temperatures, melting ice caps, sea level rise, droughts, floods, and disruption of ecosystems. It can also affect agriculture, water supply, and human health. Mitigation measures include afforestation, reduced carbon emissions, and the use of renewable energy sources.

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