Entrance Test Biology

An ecotone is a transition area between two biological communities or ecosystems. It is where two communities meet and integrate.

Nitrogen fixation is the process of converting atmospheric nitrogen (N2) into organic compounds, such as amino acids, which can be used by living organisms. While NH3 is an intermediate product, the biological goal is the synthesis of amino acids.

Azotobacter is a genus of free-living, non-legume nitrogen-fixing bacteria. Rhizobium is associated with legumes.

Ethylene is a gaseous plant hormone that promotes fruit ripening. It is commercially used to accelerate this process in harvested fruits.

Kigelia pinnata (sausage tree) is known to be pollinated by a variety of agents, including bats, birds, and insects, depending on the environment.

Cotton fibers are essentially pure cellulose. These fibers are derived from the seed coat of the cotton plant, making them seed hairs.

Algae are important because they are a potential food source (rich in nutrients) and they perform photosynthesis, which helps in purifying the atmosphere by consuming CO2 and releasing oxygen.

The middle layer of a blood vessel wall, the tunica media, is composed primarily of circular smooth muscle fibers and elastic fibers.

Broca's area (in frontal lobe) controls speech production, while Wernicke's area (temporal lobe) handles language comprehension. Speech production involves voluntary motor control of articulatory muscles. The 'voluntary action' option best fits these language centers.

A low Km value indicates a high affinity of the enzyme for its substrate, meaning the enzyme reaches half its maximum velocity at a lower substrate concentration.

Reptiles have telolecithal eggs with a large amount of yolk, which restricts cleavage to a small disc of cytoplasm at the animal pole, known as discoidal cleavage.

Embryo culture is often used to rescue embryos that would otherwise abort due to incompatibility between parents, thus overcoming hybridization barriers.

Frog eggs are mesolecithal, meaning they have a moderate amount of yolk. The cleavage is holoblastic, meaning the entire egg divides, though it is unequal.

Apogamy is the development of a sporophyte from a gametophyte cell without the fusion of gametes (fertilization).

Diapedesis is the process by which leukocytes (white blood cells) squeeze through capillary walls to reach sites of infection. The other options are unrelated: diapanse is likely misspelled, diaphysis is bone shaft, diakinesis is a meiosis stage.

Agranulocytes are white blood cells without visible granules in their cytoplasm. They include lymphocytes and monocytes. Eosinophils, neutrophils, and basophils (options A, B, C) are all granulocytes.

When malaria schizonts rupture in RBCs, they release hemozoin - a toxic byproduct of hemoglobin digestion by the parasite. Hematin is an oxidized form of heme, hemoglobin is the blood protein, and 'heam' is misspelled.

The Hardy-Weinberg principle states that a population's allele frequencies remain stable under conditions including large population size, no mutation, no migration, random mating, and no natural selection.

The vascular cambium produces secondary xylem towards the inside. Therefore, the youngest (most recently formed) layer of secondary xylem is located immediately inside the vascular cambium.

compressed biogas is a potential substitute of even petrol and diesel.

Mimosa pudica's leaf folding response (thigmonasty) occurs due to rapid turgor pressure changes in pulvini cells - specialized motor cells at leaf bases. When touched, potassium ions exit these cells, water follows, and turgor drops.