Biology: Topic-wise Test- 8 - NEET MCQ

• Phytoplanktons are small floating photosynthetic unicellular plant.
• In the aquatic ecosystem phytoplankton are producers that fix solar energy by the process of photosynthesis.

Aquatic Food Chain:

A biogeographic region with significant levels of biodiversity having a large number of endemic species that are threatened by human habitation is known as biodiversity hotspots. In all, there are 34 biodiversity hotspots present throughout the world.

Fossils are dead remains of plants and animals buried inside the earth crust millions of year ago. Fossils are commonly preserved in sedimentary rock as this kinds of rocks are formed layer by layer in course of time.

Fossils are generally found in sedimentary rocks.

A nutrient depletion zone can develop when there is rapid soil solution uptake, low nutrient concentration, low diffusion rate, or low soil moisture. These conditions are very common; therefore, most plants rely on fungi to facilitate the uptake of minerals from the soil. Mycorrhizae, known as root fungi, form symbiotic associations with plant roots. In these associations, the fungi are actually integrated into the physical structure of the root. The fungi colonize the living root tissue during active plant growth.

A total of 34 hotspots in the world has been identified till date by Norman Myers.

The materials or substances occurring in nature that exist without the actions of humankind are known as natural resources. The conservation of natural resources is important for the preservation of natural, biological diversity.

Exponential growth pattern in population results into j-shaped curve. During exponential growth faster growth occurs and j-shaped curve is formed when time v/s growth is drawn.

In ammensalism one component (population) is harmed and the other remains unaffected. The alga Microcystis release hydroxyl amine that kills the surrounding fauna but the alga itself remain unaffected. Parasitism is generally considered to deal with any small organism that live on or in another organism regardless of whether its effect is negative, positive or neutral. In predation one population adversaly affects the other by direct attack but nevertheless depends on other. In exploitation one species harms the other by making its direct or indirect use for support, shelter or food.

Ecosystem services include all activities performed by nature to benefits human beings.

The most important ecological service includes soil formation. Soil is essential for the growth of plants that provide food to all living forms.

Pyramid of energy is always erect and upright because the amount of energy get reduce at each trophic level from prouder to consumers.

Ecology is the study of the relationships between living organisms and the abiotic (physico-chemical factors) and biotic components (other species) of their environment. Ecology encompasses the interactions and relationships between organisms and both their non-living (abiotic) and living (biotic) environment. It examines how organisms interact with factors such as climate, water, soil, and other organisms.

Therefore, option a) Abiotic and biotic components accurately describes the scope of ecology.

The principle that states that the superior competitor eliminates the inferior one in competition is the Competitive Exclusion Principle. This principle suggests that when two species compete for the same limited resources in an ecological niche, the species that is better adapted or more efficient at utilizing those resources will eventually outcompete and eliminate the other species from that particular niche.

The correct answer is option a) Competitive exclusion principle. This principle highlights the competitive interactions between species and how competition can lead to the exclusion of one species by another in certain ecological niches.

This type of mutualisn to called protocooperation. In this type, the sea anemone grows on the back of the hermit crab. It protects the crab with the help of its nematocysts. Ectoparasites live on the outside of host, e.g., human body louse. In this interaction, the parasite gets the benefit at the expense of the host. Commensalism is an assotiation between organisms in which one or both the species are benefitted and neither species is harmed. In amensalism one species is harmed, whereas the other is unaffected. Predation, parasitism and commensalism share a common characteristic, the interacting species live closely together.

A carnivore population increases due to an increase in the population of herbivores. In this, an organism i.e. carnivore (predator) is benefited by killing and eating another organism i.e. herbivore (prey).

• The species of plants contribute to the traditional medicines used by native peoples around the world are approximately 25,000.
• Some examples of traditional plants used for medicinal purposes are ginger, garlic, chamomile, tulsi, etc.

Sex ratio is the no of female available per thousands of male in a population. Sex ratio is decline due to female feticides alarmingly in some part of India.

Populations grow through births and immigration and decline through deaths and emigration.

When resources become progressively limiting for a population, the growth pattern turns logistic. This means that initially, the population may experience exponential growth when resources are abundant and unlimited.

However, as resources start to become scarce and limiting, the growth rate of the population slows down and eventually levels off. This pattern is known as logistic growth.

• Exponential growth (option b) refers to a rapid and unrestricted increase in population size without resource limitations.
• Constant growth (option c) implies a steady and consistent growth rate over time, regardless of resource availability.
• Declining growth (option d) suggests a decrease in population size over time, often due to factors like limited resources or environmental disturbances.

Primary productivity is maximum in tropical rain forests due availability of sufficient food and water followed by temperate forests. Savannah grasslands have comparatively less productivity and arid regions have limited biotic component and water.

The interaction where one species benefits and the other is unaffected is called commensalism. In this type of interaction, one organism benefits from the association, while the other remains unaffected. Commensalism is characterized by a relationship in which one species gains an advantage or benefit, such as shelter, transportation, or access to food, without causing any harm or benefit to the other species involved.

The correct answer is option d) Commensalism. This type of interaction allows one species to benefit without affecting the other species positively or negatively.

• Forests helps in producing rainfall. More are the trees, the more water gets absorbed into clouds and the more it helps in rain falls. 
• The roots of a tree make gaps in the soil so that when it rains the water can sink in before being absorbed by the soil.
• These spaces also allow air and water to reach the roots of the plants.  
• If the forests disappear, there will be less rain resulting in dryer conditions, that eventually lead to drought.
• Once this happens, the damage is extensive making it difficult to plant more trees or plants later because the soil is so hard and dry. When trees removed using heavy machinery, the soil is pushed down and the gaps fill in.
• Because all plants and trees need that water and air to reach roots, the conditions become unfriendly for new growth.

Origin of universe is explained by big bang theory. According to this theory, whole universe was concentrated into single sphere. Due to same unknown region, there was explosion in it that forms different galaxies still moving away from each other.

In detritus food chain, speed of decomposition will be fast if detritus is rich in simple sugar that can be easily decomposed into glucose by saprophytes that includes bacteria and fungi.

Human belongs to a species of Homo sapiens, where Homo represents genus and sapiens represent specific epithet under the class Mammalia.

The on-site or the protection and conservation of species (genetic resources) in their natural habitat (populations of plant or animal species) is called in-situ conservation. Areas such as biosphere reserves, national parks, and wildlife sanctuaries are the places were in-situ conservation is done.

Hardy-Weinberg equilibrium cannot be disturbed by vegetative propagation as the all new offspring are clone of each other having same gene. Migration, genetic drift, mutation and natural selection affect the equilibrium of alleles in a population.

International Union for Conservation of Nature (IUCN) was founded on 5 October 1948 in France by Julian Huxley. It is working in the field of conservation of nature and sustainable use of natural resources.

According to abiogenesis theory of origin of life, life originated from non-living matter like gases, inorganic substance and water at particular temperature and pressure.

The birth rate of a population = new individual added / previous population. Here birth rate= 7/23=0.3043. Hence, birth rate of Salvinia plants is equal to 0.3.

Species area relationship is the relationship between the area and the particular habitat. It is dependent on immigration, extinction and clustering etc. It was first studied by Alexander Von Humbolt.