SAT (Stage-2) Mock Test - 61

Bryophytes are amphibians of plant kingdom. They are the oldest of all lineages of land plants and are believed to be a vital link in the migration of plants from aquatic environments onto land.

Scorpions, spiders and crabs belong to the phylum Arthropoda. An arthropod is an invertebrate animal having an exoskeleton (external skeleton), a segmented body and jointed appendages.

Coacervates were the first to be formed during origin of life.They are microscopic spontaneously formed spherical aggregates of lipid molecules that are held together by electrostatic forces and that may have been precursors of cells.

Sudden appearance of an ancestral character is called atavism. An atavism is an evolutionary throwback, such as traits reappearing which had disappeared generations before.

A cross between hybrid and either parent is called back cross. It is used in horticulture, animal breeding and in production of gene knockout organisms.

The enzyme liberated by platelet is thromboplastin. It helps in blood coagulation.

Pollination performed by bats is called cheiropterophily.Bat pollination is most common in tropical and desert areas that have many night-blooming plants.

Genetic disorders result from errors in the DNA of our body cells. Hormonal disorders (for e.g. excessive growth, appearance of facial hair in females, etc) are the results of imbalanced secretion of hormones produced within the body. Similarly, if any body organ malfunctions, i.e. it does not function in proper order, then it is an internal cause. But if there is malnutrition, then the cause is purely external and not within our body. We should remember that cause may be external or internal, but the effect is seen on the general health of our body.

This option is correct as nitrogen is required by plants in large quantity because it is a major component of chlorophyll, the compound by which plants use sunlight energy to produce sugars from water and carbon dioxide (i.e., photosynthesis). It is also a major component of amino acids, the building blocks of proteins.

(NH₄)₂CO₃ is a salt of a weak acid and a weak base. The hydrolysis reaction is:
(NH₄)₂CO₃ + 2H₂O → 2NH₄OH + H₂CO₃

Both NH₄OH and H₂CO₃ are written as unionised compounds because they are classified as weak base and weak acid, respectively.

The pH scale measures how acidic or basic a substance is. The pH scale ranges from 0 to 14. A pH of 7 is neutral. A pH less than 7 is acidic. A pH greater than 7 is basic. If the pH of a solution is zero, then the solution is highly acidic.

The molecular weight of CaCO₃ is 40.0 + 12.0 + 3(16.0) = 100 g/mol.

The bonds between N and H atoms in NH₃ are covalent.

NH₄⁺ ion is formed by a coordinate bond between ammonia and the proton. The nitrogen atom becomes the donor. The hydrogen ion becomes the acceptor. The linkage between N and H atoms is called coordinate bond. It is represented by an arrow '→'.

The bond between the ammonium ion and the hydroxide ion is ionic.

Protium (¹H₁) is an isotope of hydrgen which has 1 proton in the nucleus, but no neutrons.

The number of subshells in given n^th shell = n
Therefore, the fourth shell has four subshells named: s, p, d and f.