It is ratio of volume of CO₂ evolved and volume of O₂ consumed.
R.Q. = Volume of CO₂ evolved / Volume of O2 consumed
For proteins: R.Q. remains 0.9 and the R.Q. for fat is 0.7
2C₅₁H₉₈O₆ + 145O₂→ 102CO₂ + 98H₂O + Energy
R.Q. = 102/ 145 = 0.7

Dark reactions are dependent on light but not directly. Rather it is dependent on products of light reactions, which are ATP and NADPH. Since facilitation of dark reactions does not need light so they are called dark reactions.

Certain muscles have high concentration of myoglobin which gives it a red appearance. They also contain plenty of mitochondria which utilize large amounts of oxygen to produce ATP. Because of this they are also called aerobic muscles.

Earthworms (Pheretima) have closed blood vascular systems, which consists of the heart, blood vessels, and capillaries. The heart pumps blood for circulating it in one direction.

The root cap, a small tissue at the tip of the root, protects the root from environmental stress and functions in gravity perception. To perform its functions, the position and size of the root cap remains stable throughout root growth.

Features of Euglenoids :
i) No cell wall
ii) Protein rich layer, called pellicle, which makes flexible body
iii) Two flagella of different lengths
iv) Autotrophs in sunlight, heterotrophs in the absence of sunlight.
v) Pigmens are identical to that of higher plants.
vi) Example: Euglena

The Chlorophyceae contain chlorophyll a and b, zeaxanthin and lutein, together with a minor proportion of less typical carotenoids.

Calcitonin (Ct) or thyrocalcitonin hormone is produced by thyroid glands.
It is hypocalcaemic and hypophosphatemic peptide hormone, which checks excess plasma Ca^{2 +} and phosphate by decrease mobilisation from bones.

Atherosclerosis affects the vessels that supply blood to the heart muscle. It is caused by the deposits of calcium, fat, cholesterol and fibrous tissues, which make the lumen of arteries narrower.

The maximum absorption of digested food occurs in the small intestine of alimentary canal;.The absorbed form of different food materials are

The sodium-potassium pump helps in the active transport of ions,3Na⁺ are transported outwards and 2K inwards through the neurolemma of necrons.

This shows that the cells with 16 chromosomes are parent cells that had undergone mitotic divisions, whereas, cells with 32 chromosomes are the cells that had not undergone the process of segregation.

A nucleoside consists of a nitrogen base and a pentose sugar, but when a phosphate is added to the nucleoside, it is called nucleotide, hence, a nucleotide is a phosphorylated nucleoside.

The main structures within the cell nucleus are
(i) The nucleus which is an optically dense region, spherical shaped, where there are concentrated ribosomal RNA associated to proteins.
(ii) The chromatin made up of DAN molecules dispersed in the nuclear matrix during the cell interphase.
(iii) The nuclear membrane that delimits the nucleus.

Tendrils of grapevine and pumpkin are stem structures while those of pea are foilar in nature. Hence, the tendrils of grapevine and pea are analogous structures.

All organisms from the prokaryotes to the most complex eukaryotes can sense and respond to their environment.
The human have five sense organs, which help them to sense their environment.These are eyes, ears, nose, tongue and skin.

Conducting Part of Respiratory System. The part of respiratory system, starting with the external nostrils up to the terminal bronchioles, constitutes the conducting part. The conducting part transports the atmospheric air to the alveoli, clears it from foreign particles, humidifies and also brings the air to body temperature.

The entire process of response to a peripheral neural stimulation, that occurs involuntarily, i.e., without conscious effort or thought and requires the involvement of a part of the central neural system is called a reflex action.
The reflex pathway comprises at least one afferent neuron (receptor) and one efferent (effector or excitor) neuron appropriately arranged in a series. The afferent neuron receives signal from a sensory organ and transmits the impulse via a dorsal nerve root into the CNS (at the level of spinal cord). The efferent neuron then carries signals from CNS to the effector. The stimulus and response thus forms a reflex arc as shown below in the knee jerk reflex.

Significance of transpiration:
1.Transpiration pull facilitates movement of water from roots.
2.Transpiration supplies water for photosynthesis
3.It pulls minerals from soil.
4.Helps in cooling of plants.
5.Maintains shape of plant cells

In C₃ plants some O₂ does bind to RuBisCO, and hence CO₂ fixation is decreased. Here the RuBP instead of being converted to 2 molecules of PGA binds with O₂ to form one molecule and phosphoglycolate in a pathway called photorespiration. In the photo respiratory pathway, there is neither synthesis of sugars, nor of ATP. Rather it results in the release of CO₂ with the utilisation of ATP. In the photorespiratory pathway there is no synthesis of ATP or NADPH. Therefore, photorespiration is a wasteful process.

Every part of plant manages its gas exchange need. There is no exchange of gases between different organs. So unlike animals plants do not need special respiratory organs to facilitate exchange of gases. In leaves the exchange of gases takes place through stomata, while in stems it takes place through lenticels.

The presence of nodes and internodes on ginger gives a clue that it is not a root, but a stem.

Flowers are of ornamental value for humans and they serve a larger purpose for plants as well as for humans. Colours in flowers are meant to attract agents of pollination from the animal world. As this facilitates cross pollination so this facilitates variations leading to large diversity among plants. Because of cross pollination higher yielding and disease resistant varieties are produced which serves the food need of human. Amajor byproduct of this plant animal interaction is honey produced by honey bees. Honey has been used since ancient civilization as a food additive and as medicine

(i) The cause of Vijay's sickness is the change of altitude in which there is change in the physiology of the body.
(ii) Internal ear gets affected which control balancing of body
(iii) Eustachian tube maintains the air pressure in the ear.
(iv) The guide is a very sensible person and is caring too.

ANF is commonly known as Atrial Natriuretic Factor.
ANF is a hormone produced by the walls of the atria of the heart in response to an increase in blood volume and pressure.It increases sodium excretion and decreases blood pressure.
ANF inhibits release of renin from Juxta Glomerular Apparatus(JGA) and thereby, inhibits NaCl reabsorption by the collecting duct and reduces aldosterone release from the adrenal gland.
Function The function of counter current mechanism is to concentrate NaCl in the intestitial fluid and thereby cause water to diffuse out of the collecting tubules and ducts and concentrate the urine.

Differences between passive and active salt absorption are

(i) Figure is showing the activation energy requirement for non-catalysed and enzyme catalysed reactions.
(ii) Substances marked on arrows A and B are A - Substrate B - End products
(iii) Arrows marked shows
C-Energy of activation without enzyme.
D-Energy of activation with enzymes.
E-Free energy difference between the substrate and the end product.

Following are the labelled sections of cell membrane 
A - Cholesterol
B - Glycolipid
C - Hydrophilic head of phospholipid
D - Hydrophobic tail of phospholipid
E - Transmembrane protein
F - Intrinsic protein

Gynoecium is the female reproductive whorl of the flower. It is composed of one or more carpels. Each carpel is differentiated into three parts. i.e the ovary, style and stirma.
Placenta is the tissue on which ovule(s) develops in the ovary. The placentation in the ovary may be
(i) marginal
(ii) axile
(iii) parietal
(iv) basal
(v) free-central

The molluscs have advancement over annelids, as they have distinct head, better sense organs and gills or lungs for respiration.

Slime moulds possess the characters of both animal and fungi. Therefore, they are commonly called fungs animals. Modern biologists called them protistan fungi. They are like protozoa in their amoeboid plasmodial stage and similar to true fungi in spore formation.
Examples : Physarum, Physarella, Fuligo, Lycogala and Tubifers.

Reproduction is required for the perpetuation of a population. It is not necessary for the survival of living organism. Many organisms, e.g., mules, sterile worker bees, infertile human couples are not able to reproduce, while they have all other defining properties of life, so they can be called as living.
Sexual reproduction involves the formation and fusion of two kinds of gametes to produce an offspring. In asexual reproduction, new individuals can arise by the specialised parts of body or without the fusion of gametes.

Structure of Contractile Proteins
i) Each actin (thin) filament is made of two 'F' (filamentous) actins helically wound to each other. Each 'F' actin is a polymer of monomeric 'G' (Globular) actins.
ii) Two filaments of another protein, tropomyosin also run close to the 'F' actins throughout its length.
iii) A complex protein Troponin is distributed at regular intervals on the tropomyosin. In the resting state a subunit of troponin masks the active binding sites for myosin on the actin filaments.

Each myosin (thick) filament is also a polymerised protein. Many monomeric proteins called Meromyosins constitute one thick filament. Each meromyosin has two important parts, a globular head with a short arm and a tail, the former being called the heavy meromyosin (HMM) and the latter, the light meromyosin (LMM).

The HMI component, i.e.; the head and short arm projects outwards at regular distance and angle from each other from the surface of a polymerised myosin filament and is known as cross arm. The globular head is an active ATPase enzyme and has binding sites for ATP and active sites for actin.

Primary Structure.
The sequence of amino acids i.e., the positional information in a protein - which is the first amino acid, which is second, and so on - is called the primary structure of a protein. A protein is imagined as a line, the left end represented by the first amino acid and the right end represented by the last amino acid. The first amino acid is also called as N-terminal amino acid. The last amino acid is called the C-terminal amino acid. Aprotein thread does not exist throughout as an extended rigid rod.
Secondary Structure.
Regularly repeating local structures stabilized by hydrogen bonds. The most common examples are the alpha helix, beta sheet and turns. Because secondary structures are local, many regions of different secondary structure can be present in the same protein molecule.
Tertiary structure.
The overall shape of a single protein molecule; the spatial relationship of the secondary structures to one another. 'tertiary structure is generally stabilized by nonlocal interactions, most commonly the formation of a hydrophobic core, but also through salt bridges, hydrogen bonds, disulfide bonds, and even post-translational modifications. The term "tertiary structure" is often used as synonymous with the term fold. The Tertiary structure is what controls the basic function of the protein.
Quaternary Structure.
Some proteins are an assembly of more than one polypeptide or subunits. The manner in which these individual folded polypeptides or subunits are arranged with respect to each other (e.g. linear string of spheres, spheres arranged one upon each other in the form of a cube or plate etc.) is the architecture of a protein otherwise called the quaternary structure of a protein.

(a) Hypothalamus - Releasing hormone and Inhibiting hormone.
(b) Pituitary - Growth hormone, Prolactin, Thyroid stimulating hormone, Adrenocorticotrophic hormone, Luteinizing hormone, Follicle stimulating hormone, Melatonin.
(c) Thyroid - Tetraiodothyronine, Triiodothyronine.
(d) Parathyroid - Parathyroid hormone.
(e) Adrenal -  Adrenalin or Epinephrine, Noradrenaline or norepinephrine Corticoids.
(f) Pancreas - Glucagon, Insulin.
(g) Testis - Testosterone.
(h) Ovary - Estrogen, Progesterone.
(i) Thymus - Thymosin.
(j) Atrium - Atrial Natriuretic Factor
(k) Kidney - Erythropoietin.
(l) GI Tract - Gastrin, Secretin, Cholecystokinin (CCK)Gastric Inhibitory Peptide (GIP)

The circulatory patterns are of two types - open or closed.
Open Circulatory System. In open circulatory system blood pumped by the heart passes through large vessels into open spaces or body cavities called sinuses. Arthropodas and Molluscs have this type of circulatory system.
Closed Circulatory System. In closed circulatory system blood pumped by the heart is always circulated through a closed network of blood vessels. This pattern is considered to be more advantageous as the flow of fluid can be more precisely regulated. Annelids and chordates have this type of system.
Single Circulation. In fishes, the heart pumps out deoxygenated blood which is oxygenated by the gills and supplied to the body parts from where deoxygenated blood is returned to the heart.
Incomplete Double Circulation. In amphibians and reptiles, the left atrium receives oxygenated blood from the gills/lungs/ skin and the right atrium gets the deoxygenated blood from other body parts. However, they get mixed up in the single ventricle which pumps out mixed blood.
Complete Double Circulation. In birds and mammals, oxygenated and deoxygenated blood received by the left and right atria respectively passes on to the ventricles of the same sides. The ventricles pump it out without any mixing up, i.e., two separate circulatory pathways are present in these organisms, hence, these animals have double circulation.

The Discovery of Plant Growth Regulators:
Discovery of Auxins. Charles Darwin and his son Francis Darwin when they observed that the coleoptiles of canary grass responded to unilateral illumination by growing towards the light source (phototropism). After a series of experiments, it was concluded that the tip of coleoptile was the site of transmittable influence that caused the bending of the entire coleoptile. Auxin was isolated by F.W. Went from tips of coleoptiles of oat seedlings.
Discovery of Gibberellins. The 'bakane' (foolish seedling) a disease of rice seedlings, was caused by a fungal pathogen Gibberalla fujikuroi. E. Kurosawa reported the appearance of symptoms of the disease in uninfected rice seedlings when they were treated with sterile filtrates of the fungus. The active substances were later identified as gibberellic acid.
Discovery of Cytokinins. F. Skoog and his co-workers observed that from the intermodal segments of tobacco stems the callus (a mass of undifferentiated cells) proliferated only if, in addition to auxins the nutrients medium was supplemented with one of the following: extracts of vascular tissues, yeast extract, coconut milk or DNA. Skoog and Miller, later identified and crystallised the cytokinesis promoting active substance that they termed kinetin.
Discovery of Abscisic Acid. During mid-1960s, three independent researches reported the purification and chemical characterisation of three different kinds of inhibitors: inhibitor-B, abscission II and dormin. Later all the three were proved to be chemically identical. It was named abscisic acid (ABA). Cousins confirmed the release of a volatile substance from ripened oranges that hastened the ripening of stored unripened bananas. Later this volatile substance was identified as ethylene, a gaseous PGR.

This is a very big world and there is huge diversity of animals and plants in this world. People of different parts of the world speak different languages. Even in a country, like India, a simple bird, like crow is known by hundreds of names. Think of a scientist's difficulty in understanding about crows in different languages. Moreover, there can be thousands of species of birds. It is practically impossible to study each and every species of plants and animals. Classification makes it easy to study living beings, by keeping them under various groups and subgroups.
So, all animals which are capable of flying and have beaks are kept under Aves. Similarly, all animals, having body hair and external ears are kept under mammalia. This makes our task to study them, far easier. An easy way to study helps us in understanding the living world in a better way. It can be said that classification definitely helps in a better and systematic study of living beings.

The mode of arrangement of leaves on the stem and its branches is called phyllotaxy (Phyllon-leaf; taxis arrangement). They are arranged most systematically, regularly and mathematically, so as to get proper sunlight and avoid overcrowding.
Phyllotaxy in leaves is of following three types.
(i) Alternate: A single leaf arises at a node. e.g, China rose, mango, mustard, sunflower, etc.
(ii) Oppposite: Two leaves arise at a node,opposite to each other e.g, guava, Calotropis tulsi, etc.
(iii) Whorled: More than two leaves arise at each node forming a circle or whorl, e.g, Alstonia Scholaris etc.