Answer:(a)

The pyramid of energy is always upright because when the energy flows from one trophic level to another, some energy is always lost as heat in each step. (i) is true. Detritus food chain is the type of food chain that starts with dead organic materials. The dead organic substances are decomposed by microorganisms. (ii) is true. Many succulent xerophytes employ the Crassulacean acid metabolism or better known as CAM photosynthesis. (iii) is false. Species diversity is higher at the equator than at the poles. There might be more biodiversity near the equator because it's warmer year round, allowing organisms to continue growing.(iv) is false. A female produces a clutch of parthenogenetic (amictic) eggs. During the parthenogenetic cycle, females produce diploid eggs that develop directly into daughters. (v) is false. Answer:(b)

The basic structure of crustose lichens consists of a cortex layer, an algal layer, and a medulla. The upper cortex layer is differentiated and is usually pigmented. The algal layer lies beneath the cortex. The medulla fastens the lichen to the substrate and is made up of fungal hyphae. Answer:(d)

In warm humid climates many animals like insects, birds and mammals bear darker pigmentation than the races of some species found in cool and dry climates. This phenomenon is known as Gioger rule. (i) is false. In deep fresh water lakes, there is gradual decrease in temperature from surface to the bottom. (iii) is false. Deeper water generally results in lower light intensity and higher water pressure but greater stability of other factors in the aquatic environment, e.g. temperature and sediment characteristics. (iv) is true. Answer:(d)

Ascaris lumbricoides remains the most common endoparasite in humans. In ideal settings, Ascaris ova can persist for over 14 years. Therefore, this parasite flourishes in tropical areas where year-round transmission is possible. Both statement are true. Answer:(a)

Species may be defined as the uniform interbreeding population of individuals which freely interbreed among themselves. Answer:(a)

Answer:(a)

Red algae or Rhodophyta are mostly found in the freshwater lakes and are the oldest type of eukaryotic algae. They are red in colour due to the presence of a pigment called chlorophyll A, phycocyanin, and phycoerythrin. They also can survive at greater depths in the ocean than some other algae, because the phycoerythrin's absorption of blue light waves, which penetrate deeper than other light waves do, allows red algae to carry out photosynthesis at a greater depth. Both are correct and II explains I. Answer:(a)

Population evolves to maximize their "r" value which results in more Darwinian fitness. Increase in "r" value means birth rate is more and death rate is less. Answer:(b)

Triangular age pyramid has high proportion of prereproductive individuals, moderate number of reproductive individuals and fewer post-reproductive individuals. It represents young or rapidly growing population. Answer:(b)

A parasite is an organism that lives on or in a host organism and gets its food from or at the expense of its host. The human foetus depends during its development phase not entire life. Thus it cannot be considered as parasite. Head louse (Pediculus humanus capitis) is an obligate parasite. Female anopheles is vector and is not a parasite because they do not bite the human. Cuckoo are brood parasites as they depend on other for their young ones to develop. They are not a true parasite. Answer:(b)

Any species growing exponentially under unlimited resource conditions can reach enormous population densities in a short time. Such population shows J growth curve also known as exponential curve. Same scenario is seen inthis question. Population curve of insect is J curve. Answer:(c)

Osmoconformers are marine organisms that maintain an internal environment which is isotonic to their external environment. This means that the osmotic pressure of the organism's cells is equal to the osmotic pressure of their surrounding environment. Most osmoconformers are marine invertebrates such as echinoderms (such as starfish), mussels, marine crabs, lobsters, jellyfish, ascidians (sea squirts - primitive chordates), and scallops. There are a couple of examples of osmoconformers that are craniates such as hagfish, skates and sharks. Answer:(d)

Spores are the reproductive units similar to that of seeds which are characterized as thick-walled and highly resistant to Harsh conditions. Bacteria, fungi and lower plants survive in adverse conditions through formation of thick walled spores. Bacteria form endospores which is probably the most resistant living thing known. They may remain alive in boiling water for more than 2 hours. Answer:(d)

A biotic factor could be defined as 'the influence upon the environment of organisms owing to the presence and activities of other organisms. Biotic factors include animals, plants, fungi, bacteria, and protists. Answer:(c)

A population growing in a habitat with limited resources show initially a lag phase, followed by phases of acceleration and deceleration and finally an asymptote, when the population density reaches the carrying capacity. Answer:(c)

Age pyramid of stable population looks like a bell. Assertion is true. In a bell-shaped age pyramid, the number of prereproductive and reproductive individuals is almost equal. Postreproductive individuals are comparatively fewer. Reason is false. Answer:(c)

All the above example prove significance of temperature. Temperature is the most important ecologically relevant environmental factor. The levels of thermal tolerance of different species determine to a large extent their geographical distribution. Answer:(c)

A species whose distribution is restricted to a small geographical area because of the presence of a competitively superior species, is found to expand its distributional range dramatically when the competing species is experimentally removed. Connell’s elegant field experiments showed that on the rocky sea coasts of Scotland, the larger and competitively superior barnacle Balanus dominates the intertidal area, and excludes the smaller barnacle Chathamalus from that zone. Once Balanus is removed, Cathamalus population and distribution changes. Answer:(a)

They function as osmoregulatory organs For Marine turtle kidney is the primary organ of osmoregulation Answer:(b)

At point A, direction of curve is downward. This implies that death rate is greater than birth rate. The vital index is the ratio between natality or number of births and mortality or the number of deaths in a given time duration. The formula of vital index is Natality/Mortality x 100. Since mortality is greater than natality, vital index will be less than 100. Answer:(d)

kangaroo rat are found in North American deserts. 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. They also have a special photosynthetic pathway (CAM) that enables their stomata to remain closed during day time. Answer:(c)

Soil mesofauna are invertebrates between 0.1mm and 2mm in size, which live in the soil or in a leaf litter layer on the soil surface. Nematodes, mites, springtails, proturans, and pauropods are typical members of the mesofauna. Macrofauna, in soil science, animals that are one centimetre or more long but smaller than an earthworm. Potworms, myriapods, centipedes, millipedes, slugs, spiders are examples of macrofauna. Microfauna are the smallest of the soil fauna and are less than 0.1 mm in size, and so need a microscope to be seen. Answer:(b)

Jaundice and dengue is a serious condition. If the severity is not noticed and if it is not treated on time and lead to decrease in number of people i.e., death. Answer:(a)

When resources are limited the competitively superior species will eventually eliminate the other species, but evidence for such competitive exclusion occurring in nature is not always conclusive. The Abingdon tortoise in Galapagos Islands became extinct within a decade after goats were introduced on the island, apparently due to the greater browsing efficiency of the goats. Answer:(a)

Many freshwater animals cannot live for long in sea water and vice versa because of the osmotic problems, they would face. Answer:(d)

In the rocky intertidal communities of the American Pacific Coast the starfish Pisaster is an important predator. In a field experiment, when all the starfish were removed from an enclosed intertidal area, more than 10 species of invertebrates became extinct within a year, because of interspecific competition. Answer:(b)

Heat loss or heat gain is a function of surface area. Since small animals have a larger surface area relative to their volume, they tend to lose body heat very fast when it is cold outside; then they have to expend much energy to generate body heat through metabolism. This is the main reason why very small animals are rarely found in polar regions. Answer:(b)

Species A	Species B	Name of interaction
+	+	Mutualism
-	-	Competition
+	-	Predation
+	-	Parasitism
+	0	Commensalism
-	0	Amensalism

Interspecific interactions arise from the interaction of populations of two different species. They could be beneficial, detrimental or neutral (neither harm nor benefit) to one of the species or both. Assigning a ‘+’ sign for beneficial interaction, ‘-’ sign for detrimental and 0 for neutral interaction. Answer:(d)

Competition present between the members of the same species compete for limited resources is called Intraspecific competitions. Maximum number of individuals of a population which can be supported with optimum resources for their survival is called carrying capacity. when resources are limited, competition is maximum. Answer:(c)