(i) Hormone is called first messenger and cAMP called second messenger.
(ii) Protein hormone is water soluble, it binds to the extrinsic receptor present on the cell surface of the plasma membrane. Hormones when bind to them activates, a membrane bound enzyme adenyl cyclase, which catalyses the conversion of ATP to cAMP.
The cAMPthen activates one more enzyme known as protein kinases. After phosphorylation of protien, alteration of its function occurs which thereby, leads to some metabolic effect.

(i) Due to more activity of certain portions of phellogen, the phellem cells are cut off very rapidly and hence, these cells are loosely arranged with a lot of intercellular spaces.
These loosely arranged cells are called complementary cells and loosely arranged areas in the periderm are called lenticels.
(ii) The number of lenticels formed in a stem is variable.
(iii) Lenticels help in
(a) gas exchange.
(b) lenticular transpiration

Body elongated and metamerically segmented, presence of prostomium, characteristic mode of locomotion.

Muscles require ATP to relax as well as to contract. On animal's death, its muscles soon exhaust ATP and lose the ability to contract or relax. They become rigidly locked in whatever position they were when ATP gets completely used up. This phenomenon is known as Rigor Mortis. It is used in determining the time of death.

The layers through which the glomerular capillary blood pressure causes filtration are
i) The endothelium of glomerular blood vessels.
ii) The epithelium of Bowman's capsule.
iii) A basement membrane (present between these two above mentioned layers)

It is an electronic device, which regularly sends a small amount of electrical charge for maintaining the rhythmicity of the heart. It is implanted subcutaneously in the upper thoracic region having a connection with the heart.
The artificial pacemaker is called a life-saving instrument because, it stimulates the heart electrically at regular intervals to maintain its beats. Thus, it replaces the SA node as the originator of the cardiac impluse. It is to be noted that some pacemakers stimulate the heart at a fixed rate, others sense when the natural heart rate falls below a predetermined value and then stimulates the heart.

The foul air follows the route given below
Alveoli\(\rightarrow \)Alveolar ducts\(\rightarrow \)Bronchioles\(\rightarrow \)Bronchi\(\rightarrow \)Trachea\(\rightarrow \)Larynx\(\rightarrow \)Glottis\(\rightarrow \)Pharynx\(\rightarrow \)Internal nares\(\rightarrow \)Nasal chambers\(\rightarrow \)External nares\(\rightarrow \)Atmosphere.
The tidal volume increases 4-10 times during excitment and activity.

In male, the lateral movements of thorax constitutes 25% of breathing, while the abdominal movement accounts for 75% breathing. Thus, it regarded as abdominal breathing.
In women, particular in pregnant women, the entire breathing is through lateral movements of the thorax. thus, breathing in women is regarded as thoracic.
The VC is higher in men than in women and in the young ones than in the old persons.

The movement of air into and out of the lungs is carried out by creating a pressure gradient between the lungs and the atmosphere. The pressure within the lungs is less than the atmospheric pressure so, there is a negative pressure in the lungs with respect to atmospheric pressure. The puncture in the chest affects this pressure gradient maintained by the lungs and thus, may cause cessation of breathing

If goblet cells are non-functional for some reason, this will adversely affect smooth movement of food down the intestine due to the absence of much.
These glands secrete mucus which along with succus entericus which helps in digestion and movement of food material in the alimentary canal.

Stomach, serves as a right place due to the following reasons
(i) HCl inactivates the salivary amylase and prevents further breakdown of disaccharide carbohydrate.
(ii) It kills microorganisms and lower the pH of stomach between 1.2.5 (very acidic).
(iii) Pepsinogen (inactive precursor of pepsin) in the presence of HCl is converted into pepsin (principal protease of stomach).

If the liver would stop secreting the bile,following may happen
(i) The fats in our diet would not digested, it is because bile helps in emulsiying fats and breaks it down for the body to absorb
(ii) The liver makes bile from chlesterol.Thus,higher levels of cholesterol in the body may occur.
(iii) Bilirubin is made from our dead red blood cells and is a type of a pigment , that also acts as a part of the bile.Hence, if the liver does not secrete bile, the bilirubin would stay in blood instead of being converted by the liver into soluble form and flows with the bile.
(iv) This may our skin,white of the wyes more yellow in color(jaundice),darken our urine and the stools would be whiter in color.

The term short-day plants is actually a misnomer. When photoperiodism was discovered, the duration of the light period was thought to be critical for flowering. However, subsequently researchers found that when the long night period was interrupted in short-day plants, by a brief exposure to light, they failed to flower. In other words, the requirement is actually for a long night or a critical dark period rather than for a short day length. Thus, a short-day plant is more appropriately called as a long-night plant.
Common examples of short-day plants are Xanthium and Chrysanthemum.

Group A will show more photosynthesis.
(a) Chlorophyll absorbs maximum light in the blue region of the spectrum, i.e., 400-450 nm and hence photosynthetic rate will also be high.
Group B will show negligible amount of photosynthesis or no photosynthesis.
(b) Chlorophyll does not absorb any light in the green region, i.e., 500-550 om, but reflects green.

The leaf of the plants are heated by the temperature of the environment and also by the heat released during photosynthesis. Thus, transpiration provides a cooling mechanism for the plant to release excess heat in the leaves in order to maintain internal temperature necessary for biological and chemical processes. Transpiration tends to occur more quickly at higher temperature, i.e in suny ays due to increased evaporation. And on windy days the moisture present in the air is swept away from the leaf causing it to transpire more. Whereas on cool and calm days, the humidity rate can rise which in turn cause a decrease in transpiration.

(i) Meiosis is essential for all sexually reproducing organisms.
(ii) It occurs in reproductive cells, so that gametes formed are haploid or have half the number of chromosomes of those cells which are directly derived from zygote.
(iii) Two types of gametes fuse during the zygote formation. As a result, Zygote comes to have double the number of chromosomes contained in the gametes. Meiosis maintains a fixed number of chromosomes of a species by reducing it to number by half.

Enzymes, generally function in a narrow range of pH.Each enzyme shows its highest activity at a particular optimum pH.Activity declines both below and above the optimum value. The graph shows maximum enzyme activity at optimum pH.The rate of enzyme activity decreases above and below that optimum pH.

The sequence of amino acids, i.e., the positional configuration in a protein which is the first amino acid, which is second and so on is called the primary structure of a protein.
The first amino acid is also called as N-terminal amino acid. The last amino acid is called the C-terminal amino acid. Yes, we can connect this information to purity or homogeneity of a protein. Based on number of amino and carboxyl groups, these can be acidic (e.g., glutamic acid), basic (lysine) and neutral (valine) amino acids.

The inhibitor competes with the substract for the active sites of enzyme molecules as it has a structure similar to the substract that allows it to combine with the active site, preventing any substract molecule from occupying that site.This reduces the rate of the reaction since, the subtract can only use the enzyme molecules that are not occupied by the inhibitor, resulting in the same quantity of product being formed at a slower rate

Cycas is called the 'relic of the past' It has following properties to justify this
i) Monoxylic wood through secondary growth started
ii) shedding of seed when embryo is still immature.
iii) The arrangement of microsporangia in all defined sori.
Phylogenetically, cycas is related to the pteridosperm (seed ferns) and through them to ferns from which it seems to have evolved. It can be ascertained by the presence of 
i) lead-like megasporophyll
ii) persistence of leaf base.

The vascular plants dominated land due to the following features (any two)
(i) Presence of deep, penetrating and widespread roots which anchor the plants and also absorb water and minerals.
(ii) Covering of aerial parts with waterproof material like cutin.
(iii) Mechanical tissues are present to allow them to rise to great heights.

Protozoans take in water in bulk. As that mostly live in aquatic environments.They are highly likely to burst due to excessive in take of water.
Therefore, protozoans need to osmoregulate continuously to keep only the required amount of water in their cells. They get rid of excess water through contractile vacuoles.

Archaebacteria are able to tolerate high temperature ae well as  high acidity.
These bacteria are chemoautotrophic which obtain energy for synthesis of food by oxidising suphur. Under anaerobic conditions they oxidise sulphur to sulpuric acid.
2S + 2H₂O + 3O₂ \(\rightarrow\) 2H₂SO₄
Thermoacidophiles are able to tolerate high temperature as well as acidity, due to the presence of temperature as well as acidity due to the presence of 
(i) branched chain lipids in the cell membranes.
(ii) special resistant enzymes capable of operating under aerobic conditions.

The two kingdom classification system was given by Linnaeus in 1758. Lesser number of organisms were known then in comparison to what the world knows today. He classified all the known living beings into two categories - Animalia and Plantae on the basis of the presence or absence of cell wall in their cells. As bacteria, blue-green algae, fungi, algae, mosses, ferns, gymnosperms, and angiosperms have their cells surrounded by cell walls, unlike animals, therefore, they were placed together under kingdom-Plantae.

Viviparous animals: Viviparous animals are those animals in which both the fertilization (i.e. the fusion of male and female gametes) of egg that results in zygote and development of embryo take place inside the body of the female in the mother's womb.
These animals give birth to young ones directly.
Examples – mammals such as cows, goats, dogs, humans, etc.
Oviparous animals: Oviparous animals are those animals in which both the process of development of embryos take place outside the body of the female.
a) In oviparous animals fertilization can occur inside the mother’s body or outside the mother’s body.
b) Oviparous animals lay eggs outside their body. Example – birds, hen, frogs, etc.
Number of eggs or young ones produced by the oviparous and viviparous can be equal or not:
a) No, the number of eggs or young ones produced by an oviparous and viviparous mother cannot be equal.
b) The number of eggs laid by the oviparous animals are always more in number than the young ones produced by viviparous animals.
c) This is because the events of fertilization or development of embryos takes place outside the mother’s body so there are more chances that the eggs will get damaged prior to fertilization or development. So, to ensure the complete development of at least one embryo, oviparous animals lay more numbers of eggs than viviparous animals.
d) On the other hand in viviparous animals fertilization and development of embryos both occur inside the body of the female so there are 100% of its development.