Biology Test

The greenhouse effect occurs when certain gases (including CO2, methane, and water vapor) trap heat in Earth's atmosphere, similar to how glass traps heat in a greenhouse. This effect raises global temperatures and drives climate change.

Energy flows through ecosystems in one direction only: from the sun to producers (plants), then to herbivores, then to carnivores. Energy is lost as heat at each transfer and cannot cycle back, unlike nutrients which can be recycled through decomposition.

The ozone layer, which absorbs harmful UV radiation from the sun, is located in the stratosphere (approximately 10-50 km altitude). The troposphere is where we live and weather occurs, the ionosphere is much higher, and the lithosphere is Earth's crust.

Decomposition of organic matter (dead plants, animals, waste) is primarily carried out by microorganisms including bacteria and fungi. These saprotrophs break down complex organic molecules, recycling nutrients back into the ecosystem. Protozoa contribute to but don't drive decomposition.

The first National Park in India was set up in 1935 in the foot hills of Himalayas and was known as Hailey National Park. It is now known as Corbett National Park.

Viruses are simple infectious agents consisting of genetic material (either DNA or RNA nucleic acid) enclosed in a protein coat called a capsid. Some viruses also have an outer lipid envelope. This minimal structure allows them to replicate only inside host cells.

Tobacco mosaic virus (TMV) is a rigid rod-shaped ssRNA-containing virus that causes distortion and blistering of leaves in a wide range of plants.

Cyclostomata is a group of jawless fish that includes lampreys and hagfish. Petromyzon is the genus name for lampreys, which are classic examples of cyclostomes. The other options (channa - a fish, loris - a primate, dodo - an extinct bird) do not belong to this group.

Predation is an ecological interaction where one organism (the predator) benefits by consuming another organism (the prey), which is harmed or killed. This perfectly matches the description of a stronger partner benefiting and the weaker partner being damaged. Allelopathy involves chemical inhibition, symbiosis involves mutual benefit or close association, and commensalism benefits one partner without affecting the other.

A striking feature of cnidarians is the high degree of polymorphism often seen in a single species. Two basic types—sessile polyp and free-swimming medusa-occur.

In the taxonomic hierarchy (Kingdom, Phylum, Class, Order, Family, Genus, Species), species is the smallest and most basic taxonomic unit. A species consists of organisms that can interbreed and produce fertile offspring. Genus, order, and class are progressively higher taxonomic categories that contain multiple species.

Acid rain results from the emission into the atmosphere of various pollutant gases in particular sulphur dioxide (SO₂) and oxides of nitrogen (NO₂), which originate from the burning of fossil fuels and from motor-car exhaust fumes, respectively.

Members of Elasmobranchii subclass have no swim (air) bladders.

The endothelium lining blood vessels consists of simple squamous epithelium. This thin, single-layered tissue facilitates efficient diffusion of gases, nutrients, and waste products between the blood and surrounding tissues. Simple cuboidal epithelium is found in kidney tubules, simple columnar epithelium lines the digestive tract, and ciliated columnar epithelium is found in the respiratory tract.

Ornithorhynchus is the genus name for the platypus, which is one of only two extant species of egg-laying mammals (monotremes). The other is the echidna. Delphinus refers to dolphins, Macaca refers to macaques (primates), and Macropus refers to kangaroos - all of which are placental mammals that give birth to live young.

The sphincter of Oddi is a muscular valve that controls the opening of the common hepatopancreatic duct (also called the common bile duct) into the duodenum. It regulates the flow of bile from the liver and digestive enzymes from the pancreas. It is not associated with the pyloric stomach, esophagus, or colon.

The cardiac cycle lasts approximately 0.8 seconds at a normal heart rate of 75 beats per minute (60 seconds ÷ 75 beats = 0.8 seconds). This duration includes systole (contraction) and diastole (relaxation) phases. At this rate, the heart completes approximately 72 cardiac cycles per minute.

Prokaryotic ribosomes have 70S structure composed of large (50S) and small (30S) subunits. The 50S is the larger subunit. Eukaryotic ribosomes have 80S structure with 60S and 40S subunits. The S (Svedberg) unit measures sedimentation rate, not molecular weight, so the numbers don't add up mathematically.

Golgi complex is a part of endomembrane system, which is the system of internal membranes within eukaryotic cells that divide the cell into functional and structural compartments, or organelles.

Of the nephron segments listed, the distal convoluted tubule (DCT) has the minimum reabsorption. The proximal convoluted tubule (PCT) reabsorbs about 65% of filtrate, Henle's loop reabsorbs significant water and solutes, while the DCT only fine-tunes electrolyte balance. The collecting duct can reabsorb large amounts of water under ADH influence.

 Progestrone reaches its peak during luteal phase of menstrual cycle.