Halophytes are salt-tolerant plants that grow in waters with high salinity, such as in mangrove swamps, marshes, seashores and saline semi-deserts. Answer : (a)

Ecology is a subject which studies the interactions among organisms and between the organism and its physical (abiotic) environment. Answer : (c)

Answer : (b)

Following are the different attributes of a population: (a) Birth and Death Rates (b) Sex Ratio (c) Age Distribution Population Density Answer : (b)

Stabilizing selection is any selective force or forces which push a population toward the average, or median trait. The given data shows stabilising selection as most of the newborn having average weight between 3 to 3.3 kg survive and babies with less and more weight have low survival rate. Directional selection occurs when individuals homozygous for one allele have a fitness greater than individuals with other genotypes and individuals homozygous Disruptive selection, also called diversifying selection, describes changes in population genetics in which extreme values for a trait are favored over intermediate values. Cyclical Selection occurs when populations of a certain species are exposed to several opposing selection pressures.In dry summers, individuals with a certain phenotype can have greater fitness, while individuals with a different phenotype have greater fitness in wet summers. Answer : (b)

Fungus associated with roots of Pinus increases minerals and water absorption for the plant by increasing surface area and in turn fungus gets food from plant. Therefore, mycorrhizal association is obligatory for Pinus seed germination Answer : (b)

microbial biocontrol agents that can be introduced in order to control butterfly caterpillars is the bacteria Bacillus thuringiensis (often written as Bt ). The pH of human stomach acid is about 2 while the pH of the insect gut is about 10. Bt toxin requires a high (basic) pH to be active, and must be activated by specific protein-cutting-proteins in the insect gut. The Bt toxin is comprised of a bunch of smaller proteins that work together by teaming up to form holes in the membranes of the cells that form the gut. Answer : (c)

Both Yucca plant and the moth cannot complete their life cycles without each other. The moth deposits its eggs in the locule of the ovary and the flower in turn gets pollinated by the moth. The larvae of the moth come out of the eggs as the seeds start developing. Answer : (b)

Natality refers to the number of births during a given period in the population that are added to the initial density. Answer : (b)

Each organism has an invariably defined range of conditions that it can tolerate, diversity in the resources it utilises and a distinct functional role in the ecological system, all these together comprise its niche. Answer : (d)

Amensalism : An example of antibiosis is the interaction between Penicillium and bacteria. The mould Penicillium creates the secretion known as penicillin, which is extremely toxic to bacteria. This finding formed the basis for the first true antibiotic – called penicillin. Answer : (d)

Growing population pyramids depict populations that have a larger percentage of people in pre-reproductive individuals. Pre-reproductive individuals are greater than reproductive individuals. Answer : (c)

Rhizophora is a genus of tropical mangrove trees, sometimes collectively called true mangroves. Answer : (a)

Pistia is a genus of aquatic plants in the arum family, Araceae. hydrilla, (Hydrilla verticillata), submerged aquatic plant that is the sole member of the genus Hydrilla in the frog's-bit family (Hydrocharitaceae). Vallisneria is a genus of freshwater aquatic plant, commonly called eelgrass, tape grass or vallis. Casuarina is an evergreen tree growing to 6–35 m (20–115 ft) tall. Answer : (d)

A population pyramid is also called an age-gender-pyramid. In developing countries like India and Sudan, the population pyramid has a wide base and narrow top, i.e., population is expanding at greater rate. Rectangular shape pyramids are often characteristic of developed nations like France and Germany, where birth rates are low and overall quality of life is high. The slope of the pramid is very steep, almost vertical. Answer : (b)

Particle size	Soil type
less than 0.002 mm	clay
0.002 - 0.02 mm	silt
0.02 - 0.2 mm	fine sand particles
0.2 - 2.00 mm	coarse sand particles

Answer:(b)

Avicennia are called black mangrove. Rhizophora is a genus of tropical mangrove trees, sometimes collectively called true mangroves. Atriplex is a plant genus of 250–300 species, known by the common names of saltbush. The genus is quite variable and widely distributed. It includes many desert and seashore plants and halophytes. All the three genuses grow in high salinity, hence halophyte. Halophytes are salt-tolerant plants that grow in waters with high salinity, such as in mangrove swamps, marshes, seashores and saline semi-deserts Answer : (b)

Xerophyte, any plant adapted to life in a dry or physiologically dry habitat. Many desert plants have a thick cuticle on their leaf surfaces and have their stomata arranged in deep pits (sunken) to minimise water loss through transpiration. Xerophytes such as cacti are capable of withstanding extended periods of dry conditions as they have deep-spreading roots and capacity to store water. Answer : (d)

Hydrophytes are aquatic plants that are especially suited for living in aquatic environments. Characteristics are as follows: Floating leaves: the leaves are thin, flat and have large air spaces inside to give them buoyancy. This keeps them close to the surface of the water where there is more light for photosynthesis Thin waterproof waxy cuticle: it is very thin as there is little need to prevent water loss. Stomata located on the upper surface of the leaves: this allows for gas exchange to occur with the air instead of the water. Reduced root system: only small roots are required as they can also extract nutrients from the surrounding water through their tissues. Reduced veins in the leaves: the xylem is significantly reduced as there is no need to transport water throughout the plant Answer : (b)

Abyssal zone, portion of the ocean deeper than about 2,000 m (6,600 feet) and shallower than about 6,000 m (20,000 feet). The abyssal zone has no sunlight and extreme temperatures near freezing. It also has incredible pressure, up to 600 times that of the surface. The life that is found in the Abyssal Zone includes chemosynthetic bacteria, tubeworms, and small fish that are dark in color or transparent. Answer : (a)

World Population Day is an annual event, observed on July 11 every year, which seeks to raise awareness of global population issues. Answer : (b)

Dark brown or black color in soil indicates that the soil has a high organic matter content Answer : (b)

Endophytes are microorganisms (bacteria or fungi or actinomycetes) that dwell within robust plant tissues by having a symbiotic association. Answer : (b)

Ozone primarily occurs in the stratosphere though some ozone, approximately 10% of the total amount, exists in the troposphere. The maximum ozone concentration is between 20 and 25 kilometers (about 12 to 15 miles) above the surface. Answer:(d)

Ecological succession is the gradual process by which ecosystems change and develop over time. Succession develops through increasing complexity until it becomes stable or self-perpetuating as a climax community where the ecosystem is balanced and there is less risk of any interfering event or change to the environment. Answer:(c)

Population where pre-reproductive animals occur in large number is expanding or growing population. Answer : (d)

Species are the major subdivision of a genus or subgenus, regarded as the basic category of biological classification, composed of related individuals that resemble one another, are able to breed among themselves, but are not able to breed with members of another species. Gene flow is the transfer of genetic material from one population to another. Gene flow can take place between two populations of the same species through migration, and is mediated by reproduction and vertical gene transfer from parent to offspring. Answer : (c)

Homeostasis is any self-regulating process by which an organism tends to maintain stability while adjusting to conditions that are best for its survival. Ideally, the organism should try to maintain the constancy of its internal environment despite varying external environmental conditions that tend to upset its homeostasis. Answer : (b)

Heat ∝ Area/Volume Deer: H1 = 19,000/1,50,000 Squirrel : H2 = 625/530 H2 / H1 = 7 Answer : (a)

Typha are aquatic or semi-aquatic, rhizomatous, herbaceous perennial plants. Typha is a rooted emergent. Roots are in soil shoots or leaves are partly outside and partly inside the water. Answer : (d)