Biology Test

Caryota urens is the correct botanical name for the toddy palm (also called fishtail palm), which is tapped for its sap used to make toddy. Punica granatum is pomegranate, Achras zapota is sapodilla (chiku), and Cydonia oblonga is quince - none of which are toddy palms.

Ferns and Cycas are both cryptogams (seedless plants) that reproduce using spores. Their male gametes (sperm) are motile and flagellated (ciliated), requiring water for fertilization. They do not produce seeds, trachea, or cambium.

A strawberry is an aggregate fruit where the actual fruits are the tiny achenes (seed-like structures) on the surface. Each achene contains a seed. The fleshy red part is the receptacle (modified stem tip), not the true fruit. Therefore, strawberry is an etaerio (aggregate) of achenes.

The pyruvic acid transported into the mitochondrial matrix is not directly used in the Krebs cycle. First it loses a molecule of CO₂ as NAD⁺ is reduced to NADH. The remaining molecules, called acetyl group, attaches to coenzyme to form acetyl coenzyme A. The conversion of  pyruvic acid to acetyl CoA links glycolysis and the Krebs cycle. Pyruvic acid is the final product of glycolysis and acetyl CoA is the compound that enters the Krebs cycle.

Cytochrome c reductase (Complex III) is located on the outer membrane of mitochondria in the electron transport chain. Adenylate kinase and ATP synthetase are primarily associated with the inner membrane, while nucleoside diphosphokinase is mainly cytosolic.

In Cycas, the vascular bundles in the rachis are arranged in an omega-shaped ring (Ω-shaped). This is a characteristic feature of cycad stems, where the xylem and phloem are organized in a curved, horseshoe-like pattern that resembles the Greek letter omega.

Saprophytes are those plants which grow on dead and decaying organic matter of animals and plants. Neottia grows on humus rich soil. The plant has underground rhizome which form a cluster of roots. The roots of Neottia are associated with endotrophic mycorrhiza.

In dicots, the most common type of pollen tetrad arrangement is tetrahedral, where the four microspores are arranged in a three-dimensional pyramid-like structure. This occurs when microspores divide in all planes. Isobilateral is more common in monocots, while linear and decussate are less frequent patterns.

When all tissues except xylem are removed, the root will die first. This is because roots depend on energy (ATP) from photosynthesis occurring in leaves, which requires phloem for sugar transport. Without phloem, roots cannot receive the organic nutrients needed to sustain cellular respiration and growth. Leaves and stem may survive temporarily on stored nutrients, but roots are most distant from these reserves.

Clostridium is a free-living anaerobic nitrogen-fixing bacteria. It lives in soil and fixes nitrogen without requiring oxygen or a host plant. Rhizobium is symbiotic (requires legume host), Azotobacter is aerobic (requires oxygen), and Nitrobacter is a nitrifying bacteria that converts nitrite to nitrate but does not fix nitrogen.

The leaves in Selaginella are ligulate, in that they bear a flap like or finger like projections at the base called the ligule.

Active mineral absorption requires energy (ATP) because minerals are moved against their concentration gradient from soil to root cells. This is an active transport process facilitated by carrier proteins in the cell membrane. Active water absorption is passive (osmosis), photophosphorylation produces ATP but doesn't directly drive mineral uptake, and vascular bundle cells facilitate transport but don't power it.

Aerobic respiration is the oxidative breakdown of respiratory substrates (like glucose) with the help of oxygen, producing CO2, water, and ATP. Anaerobic respiration occurs without oxygen, fermentation is a type of anaerobic respiration in yeast/bacteria, and respiratory quotient is the ratio of CO2 produced to O2 consumed.

The normal phenotypic ratio for a dihybrid cross (two traits, both heterozygous parents) is 9:3:3:1. This represents 9 dominant for both traits : 3 dominant for first trait only : 3 dominant for second trait only : 1 recessive for both traits. 3:1 is the monohybrid ratio, and 9:3:4 and 12:3:1 are modified ratios seen with epistasis or lethal genes.

Sacchromyces (yeast) belongs to unicellular, nonmycelial ascomycetic fungus

Chlorophyll-a is found in all groups of algae and is the universal photosynthetic pigment. It's the primary reaction center pigment in all photosynthetic organisms. Chlorophyll-b is found in green algae and plants, chlorophyll-c in diatoms and brown algae, and chlorophyll-d in some red algae - but only chlorophyll-a is truly universal across all algal groups.

During pachytene stage of meiosis I, each non-sister chromatid of homologous chromosomes exchange segments. This point of contact where crossingover takes place is termed as chiasmata.

Passage cells (also called transfusion cells) are thin-walled endodermal cells found opposite to protoxylem patches. They lack Casparian strips and allow water and minerals to bypass the endodermal barrier, facilitating transport to the xylem. Sclereids are thick-walled supportive cells, and epiblema (rhizodermis) is the root epidermis.

In CAM (Crassulacean Acid Metabolism) plants, phosphoenol pyruvic acid (PEP) is the primary CO2 acceptor. During the night, PEP carboxylase fixes CO2 into oxaloacetate (which is converted to malate). During the day, malate releases CO2 for the Calvin cycle. Phosphoenol pyruvate is the 3-carbon compound that accepts CO2, not ribulose biphosphate (RuBP - used in C3 and C4 plants) or the other options listed.

Food products are refrigerated because very low temperatures drastically reduce respiration rates in plant tissues, slowing down metabolic processes that cause spoilage. This preservation method maintains flavor, texture, and freshness by preventing the breakdown of sugars, starches, and other compounds that would otherwise occur through respiration and microbial growth at higher temperatures.

The increase in respiration rate during fruit ripening in climacteric fruits like bananas is called the climacteric (or climacteric rise). This burst of respiration (with ethylene production) marks the transition to ripening. Anthesis is flower opening, climax is an ecological term, and photorespiration is a light-dependent process in plants that consumes oxygen and releases CO2.

Chemosynthesis occurs only in colourless aerobic bacteria such as, Nitrosomonas, Nitrobacter etc.

The diversity-stability hypothesis proposes that ecosystems with higher species diversity are more stable and better able to resist disturbances. This is because diverse ecosystems have more functional redundancy and complex food webs that can buffer against the loss of any single species. The other hypotheses listed relate to plant physiology (Raunkiaer's) or unrelated ecological concepts.

The disaccharides are most abundant oligosaccharides in the cells. They are called double sugars. Biologically important double sugars are lactose, maltose and sucrose.

HIV (human immuno deficiency virus) is positive-strand retrovirus, which has singlestranded RNA as the genetic material