31 Year NEET Previous Year Questions: The Living World- 1

• Muscidae are commonly known as house flies or stable flies.

• These are found worldwide in distribution and contain almost 4,000 described species in over 100 genera.

• Additional Information

  • Anacardiaceae: It is famous as the cashew family or sumac family. Anacardiaceae include numerous genera, like cashew (in the type genus Anacardium), mango, poison ivy, poison oak.

  • Hominidae: Hominidae family is one of the two living families of the ape superfamily Hominoidea. This family includes apes like orangutans (genus Pongo), the gorillas (Gorilla), and the chimpanzees as well as human beings (Homo).

  • Poaceae: This family is a large and nearly ubiquitous family of monocotyledonous flowering plants known as grasses. This family includes the cereal grasses, bamboos, and the grasses of natural grassland.

• According to Binomial Nomenclature, the first word denoting the genus starts with a capital letter while the specific epithet starts with a small letter
• Example: Scientific name of mango is Mangifera indica.
• The author's name appears after the specific epithet, i.e., at the end of the biological name, and is written in an abbreviated form.
• Example: Mangifera indica Linn. which indicates this species was first described by Linnaeus.

Photoperiod affects the reproduction in plants by regulating the flowering timing of the plants. The binomial system of nomenclature was given by Carolus Linnaeus. R. H. Whittaker proposed 5 kingdom classification of living organisms.

Binomial nomenclature (also called binomial nomenclature or binary nomenclature) is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages.

• Basal metabolic rate is the amount of energy used per unit time by an organism. It can be measured in various units including watt, joule per hour. Basal metabolic rate affects the number of calories used up by a person. The processes which require energy are breathing, blood circulation, cell growth, and contraction of muscles.
• Oxygen consumption is the amount of oxygen required by the body and taken in while respiration per minute. It is also called the rate of oxygen used. An increase in the ventricular volume and an increase in the blood pressure both factors are involved in the increase of oxygen demand.
• Whenever we do heavy exercise there is not enough oxygen available in our body which causes anaerobic metabolism to occur in the body. This leads to the formation of lactic acid in the body. It causes discomfort to the body.

• Museum – Biological museums are generally set up in educational institutes such as schools and colleges.
• Museums have collections of preserved plant and animal specimens for study and reference.
• Specimens are preserved in containers or jars in preservative solutions.
• Plant and animal specimens may also be preserved as dry specimens.
• Insects are preserved in insect boxes after collections, killing and pinning.
• Larger animals like birds and mammals are usually stuffed and preserved.
• Museums often have collections of skeletons of animals too.

• As per the  International Rules of Nomenclature, the scientific name consists of two parts, genus and species.
  Both genus and species are either italicized or are underlined. In the genus, the first letter is capital whereas the species name is always written in lower case letters. 
• Musca domestica is the common housefly. In option A, the scientific name is not italicized. 
• Plasmodium falciparum is a protozoan pathogen causing the most serious type of malaria. 
• Felis tigris is the scientific name of the Indian tiger. In option B, the first letter of genus Felis is not written in capital letter. 
• Escherichia coli is the full name of E. coli. It commonly occurs in human intestine.

Metabolism is the process by which all living things assimilate energy and use it for various purposes such as growth, movement, locomotion etc. This mechanism of metabolism is not shown by nonliving objects. However, some of the metabolic reactions can be carried out in a cell-free system or outside the cells. Isolated metabolic reactions in vitro are not living things but are living reactions. Hence, statement A is incorrect.

All living organisms show growth either by multiplication or by an increase in size. It is an irreversible increase in the mass of individual from inside. Two types of substances are produced by the cells, apoplastic and protoplastic. Apoplastic substances are nonliving materials formed by the cells which become components of tissues. For example, cell wall, the matrix of bone etc. Protoplastic substances are the components of living matter like cytoplasm and nucleus.

Although some nonliving things like mountains, sand mounds, crystals also grow, their growth is due to the addition of matter from outside.

Hence, statements B and D are incorrect.

All organisms respond to external stimuli which can be physical, chemical or biological. This is called irritability. Stimuli are perceived by sense organs in animals but plants can respond to external factors like water, temperature, light etc. All organisms from prokaryote to the most complex eukaryotes can sense and respond to environmental events.

Hence, statement C is correct.

So, the correct answer is 'Perception of events happening in the environment and their memory'.

Seed habit is the ability to form seeds.

• Dependent sporophyte is found in Bryophytes and it is dependent on the gametophyte for nutrition.
• Heterospory is the production of spores of two different sizes and two different development patterns. Small spores are called the male spores or microspores and the larger spores are called female spores or megaspores. Heterospory is an expression of sex determining process of the plants. It is the most important evolutionary development in the vascular plants because it ultimately leads to the seed development.
• Haplontic life cycle is a primitive type of life cycle which is characterized by zygotic meiosis and haploid adults.
• Free living gametophyte is the one that does not depend on sporophyte for its nutrition. Hence, heterospory leads to development of seed habit. 

So, the correct answer is 'Heterospory'.

The oxygen is needed for aerobic respiration and diffuses from a region of high to low concentration from the mother's blood to the blood of the foetus. The haemoglobin of the foetus has a higher affinity for oxygen than that of adult haemoglobin and so the efficiency of exchange is increased.
So, the correct answer is 'Has a higher affinity for oxygen than that of an adult'

To survive in a particular environment, an organism need to adapt to that environment. If the organism becomes a success in adapting them that organism is selected by nature.

• Biological organisms start with the submicroscopic molecular level like viruses, bacteria etc.
• These organisms are unable to be seen by naked eyes without the help of a microscope or even an electron microscope.

• Gene flow is the spread of genes through populations as affected by movements of the individual and their propagules
  Example: Seeds spores
• Gene flow ensures that all populations of a given species share a common gene pool. i.e. it reduces the difference between populations.
• The interruption of gene flow between populations is a pre-requisite for the formation of new species.

• Angiosperms have adapted themselves to all kinds of habitat - terrestrial, aquatic, tropical, deciduous and alpine.
• Self-pollination is seen in very few angiosperms.
• Production of a large number of seeds ensures that at least some will germinate.
• Not all plants have been domesticated by man.

Phenetic classification is based upon observable characteristics of an  organism. Phylogenetic system of classification is a system indicating the evolutionary or phylogenetic relationship of organisms.

•  The word cryptogam came from the greek word cryptos - hidden; gamos - marriage.
• The sporophyte is a stage in the life cycle of a plant. In ordinary conditions it always diploid.
• Thallophytes are the group of lower plants that do not have vascular supply,
  Example: Bacteria, algae, fungi etc.
• Bryophyta is a group of cryptogams that has an amphibious type of adaptation.

• In biology, a species is one of the basic units of biological classification and a taxonomic rank.
• A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring.
• While in many cases this definition is adequate, more precise or differing measures are often used, such as similarity of DNA, morphology or ecological niche.
• The presence of specific locally adapted traits may further subdivide species into subspecies. 

• Biosystematics is the study of biological diversity and its origins. It focuses on understanding evolutionary relationships among organisms, species, higher taxa or other biological entities, such as genes and the evolution of the properties of taxa including intrinsic traits, ecological interactions, and geographic distributions.
• An important part of systematics is the development of methods for various aspects of phylogenetic inference and biological nomenclature.
• Whereas morphological characteristics ( physical appearance) and cytological characteristics ( size of cell and nucleus) are not used for systematics.

• The organisms obtaining energy by chemical reactions independent of light are called chemotrophs.
• When the reductants obtained from the environment in the inorganic form then organisms are chemoautotrophs. While when it is organic then organisms are chemoheterotrophs.
• Photoautotroph makes their food by photosynthesis using the energy of the sun.
• Saprozoic organisms obtain food from dead and decaying matter.

Individuals of the same species can interbreed. No two individuals share the same ecological niche.

The five-kingdom classification is a mode of classification based on the following criteria: 

• The complexity of cell structure.
• The complexity of body structure.
• Modes of nutrition  
• Ecological lifestyles  
• Phylogenetic relationship

Early conditions on earth were high temperature, volcanic eruptions, lightning and a reducing atmosphere (because there was no oxygen), so an organism that can survive in these extreme conditions might have lived on the early earth. Therefore, among given options, chemoheterotrophs fit right in the given situations.

It is presumed that the first living organisms were chemoheterotrophs that obtained energy by the fermentation of complex organic substances available to them from the sea broth. They were anaerobes.

Photolithotrophs manufacture their own organic nutrients from inorganic raw materials (H₂, O₂) with the help of radiation energy. 

The correct hierarchy of classification of various taxons in descending order is given by:
Kingdom → Phylum → Class → Order → Family → Genus → Species

The kingdom is the highest taxon with the least similar characters shared between its various members while the species is the lowest level with almost similar morphological and behavioural similarities. Species is followed by Genus with slightly fewer similarities among its members.

• Species' is less general in following to genus. 
• Species are the smallest group among all the eight levels of taxonomy with almost similar characters.
• It is followed by Genus with slightly fewer similarities among its members.
• Examples: Armadillo – Dasypus novemcinctus, Cat – Felis catus, etc.

Hence, ‘species’ is the correct answer.

Relative Biological Effectiveness (RBE) allows comparison of a test radiation with a standard radiation. It is the ratio of dose between the radiations to give a certain biological effect, for instance a grade of skin reaction or death of mice. 
So the answer is  'Radiation'.

• Reproduction is necessary for continuity of life. However, the production of gametes is not the only method for this.
• A number of organisms reproduce asexually. In any case, cell division is necessary which involves replication of DNA.

• An artificial system of classification is based on a comparison of one or a few characters.  
• A system based upon a large no. of natural characters or traits is a natural system of classification, Proposed by de Jussieu.
• The phylogenetic system of classification indicates the evolutionary or phylogenetic relationship of organisms.

• Biological classification is the scientific arrangement of organisms in a hierarchical series of groups and subgroups on the basis of similarities and differences in their traits.
• It helps in building evolutionary pathways and in identifying new organisms.
• The practical purpose of the classification of living organisms is to facilitate the identification of unknown organisms.
• It helps in building evolutionary pathways and in identifying new organisms.

Linnaeus put forward an “Artificial system” of plant classification which was based on sexual characters. It is commonly also called as Sexual System of plant classification.