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Key Points

• Globular proteins are named such for their spherical shapes.
• They are the most abundant proteins of all.
• They are formed of polypeptides like other proteins but are folded into tertiary structures.
• They may form a variety of structures containing α-helices and β-sheets folded into 3D structures.
• This gives them a roundish structure which gains stability by the intrachain bonds.
• They are usually water-soluble because of the hydrophilic amino acid side chains that lie on the surface.
• The diversity of the structures help them to perform diverse functions in organisms.

Explanation:

• Most of the enzymes are globular proteins which have specific functions because of their tertiary structures.
• They can also act as hormones. Example- Insulin hormone.
• Antibodies belong to a group of globular proteins called immunoglobulins. Example- IgA, IgE.
• Haemoglobin is another globular protein present in the blood that helps to bind and transport oxygen in the body.
• But globular proteins do not function as structural molecules.
• The fibrous proteins, which have a linear structure, function as structural proteins. Example- Keratin in hair and nails.

The correct answer is Both (A) & (B).

Concept:

• Inflorescence: Some flowers bloom in bunches while some others bloom vertically**.** This arrangement of flowers on the floral axis (stem) of flowering plants in biology is called Inflorescence. 
• Floral axis is a part of flower on which reproductive organs and other parts of flower are attached).
• Types of Inflorescence: Depending on whether the apex gets converted into a flower or continues to grow, two major types of inflorescences are defined as:
• Racemose - The peduncle grows indefinitely and bears flowers in acropetal order.
• Cymose - The main axis stops growing and terminates in a flower which are formed in basipetal order.
• Acropetal means having the younger flowers at the apex, while basipetal means having the older ones near the apex.

Important Points

• Dichasial cyme Inflorescence (A type of Cymose inflorescence)
• Here, the peduncle (a stalk of flower) ends in a flower, and from the basal part of it, two lateral branches arise, hence has limited growth.
• The flowers are borne in a basipetal order.
• These also end in a flower and this same arrangement occurs on these lateral branches.
• It is usually seen in Solanaceae Family. Ex. Jasmine, Teak, Bougainvillea.

​

• Verticillaster Inflorescence (A type of Cymose inflorescence)​
• In this type, there is a cluster of sessile or subsessile flowers borne on a dichasial cyme ending in monochasial cyme in the form of condensed whorl on either side of the node.
• It is seen in Labiatae / Lamiaceae Family.
• Example: Ocimum (Tulsi), Mint, Coleus, Mustard etc.

​

Lamiaceae family plants like Tulsi (Ocimum sanctum) exhibits mixed inflorescence, i.e. both Verticillaster & dichasial cyme type of inflorescence.

Concept-

A population is defined as a group of individuals of the same species living and interbreeding within a given area.

Key Points Deme-

• A deme is a sub-population (a smaller group within the population) that can freely interbreed.
• Population is usually made of several demes (groups) that are partially isolated from each other.
• Often a geographical barrier limits gene flow between demes, but not sufficiently to result in speciation.
• The deme usually is not a closed population but contributes individuals to neighbouring populations and receives immigrants from them.

Additional InformationCloning- Cloning is the production of a population of genetically identical cells or of organisms asexually produced by a single cell or organism. Cloning is fundamental to most living things, since the body cells of plants and animals are clones that come from a single fertilized egg.

Hybrid- a plant or animal that has been produced from two different types of plant or animal.

Niche- Niche is used to describe the role an organism or population plays within its community or ecosystem.

Concept-

• Ribosomal RNA or rRNA molecules are synthesized in a specialized region of the cell nucleus called the nucleolus, which appears as a dense region within the nucleus and contains genes encoding rRNA.

Key Points

• Ribosomal RNA (rRNA) is a molecule in cells that is part of protein-building organelles called ribosomes and is exported to the cytoplasm to help translate the information contained in messenger RNA (mRNA) to proteins.
• The encoded rRNAs are of different sizes, differentiated into large or small.

Each ribosome contains at least 1 large rRNA and at least 1 small rRNA.

• In the nucleolus, large and small rRNAs combine with ribosomal proteins to form large and small ribosomal subunits (eg, 50S and 30S in bacteria, respectively).
• These subunits are usually named for their settling rate, measured in Svedberg [S] units, in the centrifugal field.
• Ribosomal proteins are synthesized in the cytoplasm and transported to the nucleus to be reassembled in the nucleus.
• The subunits are then returned to the cytoplasm for final assembly.
• Prokaryotes have 70S ribosomes that has 50S and 30S subunits, while eukaryotes have 80S ribosome which has a 60S and a 40S subunit.

Additional Information

Protein

• These are the products formed from the genetic information present in a cell.
• They help in carrying out the various metabolic activities of the cell to sustain life.
• mRNA is converted into a protein by the process of translation.

Messenger RNA

• ​This type of RNA functions by transferring the genetic material into the ribosomes and passing the instructions about the type of proteins, required by the body cells.
• We can also say Information from the nucleus to the cytoplasm is carried by m-RNA.
• Based on the functions, this type of RNA is called messenger RNA.
• Therefore, the mRNA plays a vital role in the process of transcription or during the protein synthesis process.

Transfer RNA

• These are RNA molecules that transfers amino acids to the ribosome complex during protein synthesis process.
• Each tRNA carries an amino acid at one end and has an anticodon sequence at another end, which can bind to its complementary sequence on the mRNA.
• Thus tRNAs are adapter molecules that help in reading the genetic code on the mRNA and accordingly add amino acid to the growing peptide chain.
• These are specific for each amino acid.

Concept-

• Growth in plants takes place in two ways:
• Primary growth - It is the main form of growth in a plant that mostly occurs due to activity of apical meristems.
• Secondary growth - This is found in most dicot plants exhibiting an increase in girth.
• Secondary growth is caused by 2 lateral meristems:
• Vascular Cambium - It is responsible for forming secondary xylem and secondary phloem.
• Cork Cambium - It forms the periderm (bark) towards the outer periphery in older plants.
• The cork cambium is also known as the phellogen.

Key Points

• The cork cambium is a type of meristematic tissue present in many vascular plants.
• It usually develops in the cortex region as the stem grows in girth.
• Between the cork and primary phloem, it is one of the several layers of bark. Cork cambium is a lateral meristem that is responsible for secondary growth in roots and stems.
• It can be found in a variety of woody and herbaceous dicots, gymnosperms, and monocots (monocots lack secondary growth).
• The phellogen can be a couple of layers thick and made up of narrow, thin-walled, rectangular cells.
• It can cut off cells on both sides, producing outer and inner cells.
• The outer cells differentiate into the cork or phellem and the inner cells differentiate into the secondary cortex or phelloderm.
• The phellem is impervious to water because of suberin depositions in its cell walls, while phelloderm cells are parenchymatous.
• Phellem, phellogen and phelloderm are together called as the periderm.
• The phellogen may sometimes also form lenticels on the outer surface of the bark through which gaseous exchange may take place.

Additional Information

• The Secondary cortex is a cellulosic cell walled parenchyma cell with a thin wall. Cork and cambium make up the material.
• Cork is an impermeable material, the phellem layer of bark tissues. Cork is composed of suberin, a hydrophobic substance.

The correct answer is D-amino acid.

Explanation:

• Proteins (“proteios” which means - prime importance) are building blocks of all living organism and are the major structural component of cells and is responsible for the building and repair of body tissues.
• All proteins are polymers made up of amino acids. Amino acids contain Amino (–NH₂) and Carboxyl (–COOH) functional groups.
• Amino acids are compounds made up of Carbon (C), Hydrogen (H), Nitrogen (N), and Oxygen (O).
• Some amino acids like methionine and cysteine sometimes contain a small amount of Sulfur (S) & Iron (Fe) in addition to C, H, O, N.
• Phosphorous is generally absent from the primary structure of proteins.

D-amino acid :

• Amino acids refer to compounds whose molecules contain an amine group (-NH2) and carboxyl group (-COOH).
• All amino acids except for glycine are stereoisomers. This means that there are mirror images of their structure. It is just like how we have left hands and right hands.
• These are labeled L (left-handed) and D (right-handed) to distinguish the mirror images.
• D-Amino acids are occasionally found in nature as residues in proteins.
• Most of the proteins contain L-amino acids.

 Additional Information

• Based on the source from which proteins are derived, they are categorized into two main categories –

           i) Animal-based protein           ii) Plant-based proteins

Concept-

Pine moss or wolf moss (Letharia vulpina**) is** a beautiful greenish-brown, bushy moss that grows on the bark of pine and fir trees in the Pacific Mountains of the United States and contains a moderately toxic yellow dye called vulpinic acid.

Key Points

• The thalli or main body is bushy and densely branched, from bright yellow to yellow-green or greenish-yellow, but fades in dry specimens.
• Sizes are typically 2 to 7 cm (0.8 to 3 inches) in diameter.
• There are many Soredia and isidia of vegetative reproductive structure on the surface of the thallus.
• Letharia vulpina is found throughout the Pacific Northwest. Often abundant on bare branches that have lost their bark.
• In old wet forests, they are usually found in dry areas. This species is moderately sensitive to air pollution.
• In the Rocky Mountains, Letharia species is found in the Ponderosa forests on the prairie border at relatively low elevations, but in the Douglas spruce and pine forests at medium to high elevations.

Additional Information

• Also known as true Icelandic moss or Icelandic moss, Cetraria islandica seems to be derived from the name of an upright or upright Icelandic moss whose leaf shape looks like moss.
• Cladonia rangiferina, also known as crustacean moss, deer moss, or grey deer moss, is a species of brightly coloured shrub moss in the family Cladoniaceae. It grows in hot and cold climates in an open environment with good drainage.
• Lecanora esculenta has an approximately round fruit disk (apothecia) bordered by photosynthetic tissue resembling body parts that are not fruiting bodies of lichens (thallus).

Concept-

• Obelia is a genus of hydrozoans, a class of mainly marine and some freshwater animal species that have both polyps and medusae in their life cycle.
• Hydrozoa belongs to the class Cnidaria, which are aquatic (mainly marine) organisms that are relatively simple in structure.
• They are commonly called sea-fur.
• The polyp is the sessile and asexual stage, while medusa is the free-swimming, sexual stage.
• They form small hydroid colonies on rocks or large seaweeds in the form of fur-like growth.

Explanation:

• Coenosarc -
• It is the inner, tubular, living tissue of Obelia colony.
• It encloses a canal called gastrovascular cavity.
• It is surrounded externally by perisarc.
• Perisarc -
• It is the yellow-brown, non-living chitinous layer of Obelia.
• It protects the colony and acts as an exoskeleton.
• It contains annuli that allows some limited movements.
• Medusae are lateral buds that develop as a result of asexual reproduction from the blastostyle.
• Thus medusa is not covered by the perisarc.

Key Points Medusa-

• The medusa may be an adjusted zooid delivered as an empty bud from the coenosarc of the blastostyle in spring and summer. Medusa swims unreservedly on the surface water.
• It is saucer-shaped and joined to the blastostyle by the centre of the raised surface. When completely shaped it breaks free and develops from the mouth of the gonotheca.
• The medusa is circular and modest umbrella-like in shape.
• The arched external surface is known as the ex-umbrella and the concave inward surface is the sub-umbrella.
• From the middle of the sub-umbrella emerges a brief anticipating manubrium, at its pinnacle may be a square mouth encompassed by four verbal projections.
• The mouth leads into an enteric depth or gastric depth within the manubrium.
• From the enteric depth, emerge four outspread canals which are sensitive ciliated tubes, they run to the edge of the chime to connect a ciliated circular canal running close the margin.
• The enteric depression and the canals speak to the enteron which disperses nourishment.
• Anticipating from the centre of the spiral canals are four gonads, since genders are isolated they are either four testicles or four ovaries, they are patches of altered sub-umbrella ectoderm.
• The gonads develop after the medusae elude from the gonotheca.
• The edge of the chime is created inwards as a lean crease called velum.

Additional Information

• The hydranths are nourishing polyps, they nourish by capturing diminutive creatures and hatchlings.
• Towards the base of the hydrocaulus within the axils of the polyps, are regenerative polyps called blastostyles.
• The blastostyles are the regenerative zooids as they replicate asexually to allow rise to various sidelong buds called medusa buds or gonophores.
• These buds create into third sort of zooids of the colony called medusae.
• The polyps, their tubular associations and blastostyles are made of ectoderm, mesogloea and endoderm, these layers are together called coenosarc and its depth is an enteron that is ceaseless and common to all the individuals, through the enteron processed nourishment is disseminated in arrangement.

Concept:

• Enzymes are protein molecules that act as biological catalysts.
• They help in increasing the rate of chemical reactions that take place in living beings.

Explanation:

• All require a coenzyme for their activity: NOT TRUE
• ​Coenzymes are non-protein, organic molecules that can bind to enzymes to enhance or facilitate the enzyme activity.
• They are usually vitamins or vitamin derivatives.
• ​But not all enzymes require coenzymes to function.
• All are active at neutral pH: NOT TRUE
• ​The optimum pH of an enzyme depends on the location where it functions.
• For example, stomach enzymes function in acidic pH, while in small intestine enzymes function in a slightly basic pH.
• Therefore, all enzyme activity do not occur at neutral pH.
• All require a molecule of water for their activity: NOT TRUE
• ​Enzyme activity has been found to be enhanced in the presence of water.
• However, enzymes may still be functional in the absence of water.
• All lower the energy of activation: TRUE
• ​Enzymes increase the rate of reaction by lowering the activation energy.
• Activation energy is the minimum amount of energy required to activate atoms or molecules so that they can undergo chemical transformations in a reaction.
• The lower the activation energy, the faster will be the reaction catalyzed by an enzyme.

The correct answer is 21.

Concept:

• Development of the fertilized zygote into a fully developed foetus or a young one is known as embryogenesis.
• This process can take place in 2 main ways:
• Oviparous - In this type, the development takes place outside the female body. The female lays fertilized eggs and then incubates them to hatch.
• Viviparous - In this type, the development takes place inside the mother's body, such that the mother gives birth to the young ones.
• All birds are oviparous in nature and thus they lay eggs.

Explanation:

• After fertilization, the zygote divides repeatedly and travels down the oviduct.
• As it descends, many protective layers form around it.
• The hard shell in a hen’s egg is one such protective layer.
• The hen finally lays the egg after the hard shell has formed around the developing embryo.
• It takes about 3 weeks (21 days) for the embryo to develop into a chick.
• The mother bird sits on the eggs after they are laid to keep them warm. This process is known as egg incubation.
• The embryos continue to develop within their egg shells.
• After the embryos develop, the eggs hatch.
• The incubation period is different for different birds.

So, the incubation period in chick lasts for 21 days.