Prolactin, also called as luteotropic hormone (LTH) or luteotropin, is a protein hormone produced by the pituitary gland of mammals, that acts with other hormones to initiate secretion of milk by the mammary glands. 

Prolactin is the hormone that stimulates milk production. During pregnancy, prolactin stimulates growth of the breast, but high estrogen and progesterone secretion prevent milk production. After delivery, estrogen and progesterone levels drop, and prolactin stimulates the secretion of milk by alveolar cells in the breast.

Lemmings reduce their number by committing suicide every 4 years. It has been regarded as a collective suicide, conscious or involuntary, caused by overpopulation. In reality, being solitary rodents by nature, when the population booms, the stronger lemmings drive the weaker and younger ones off long before the food is depleted.

Guttation is a process of oozing out of the xylem sap on the margin of the leaves through specialized openings called hydathodes. Guttation is also known as bleeding of the leaf.

As the temperature increases, it makes the surrounding air dry that causes the rate of transpiration to increase. The increase in temperature results in a higher vapour pressure gradient. With the decrease in temperature, transpiration also decreases.

Both the grapes as well as honey are highly concentrated solutions. So, when grapes are placed in honey, no net movement takes place. Honey forms an isotonic solution with respect to grapes.

Due to Industrial melanism, refers to the evolution of dark body colours in animal species that live in habitats blackened by industrial soot. The phenomenon has been documented in numerous species that hide from predators by blending in with their backgrounds. The main predator is bird.

Natural selection is the process where organism with favorable traits are more likely to reproduce. In doing so, they pass on these traits to the next generation. Over time this process allows organism to adapt to their environment.

For the purpose of avoiding being noticed and to save itself successfully from the snake, the prey becomes motionless. It ambushes itself well with the surroundings. The ambush may be set by hiding in a burrow, by camouflage, by aggressive mimicry, or by the use of a trap.

• Instinct behaviors are innate abilities. They occur and are present from birth onward and are not learned behaviors. It is performed by all members of their species. They are typically a fixed action pattern (FAP) that occurs as a result of a specific stimulus. For example, spinning a web by a spider, nest building and other maternal activities, migration patterns of animals, social behavior in pack animals, swimming by fish, etc.
• Hence, fish do not need to learn how to swim is an example of instinct behavior.

The action does not involve the brain and is an example of a simple reflex. When the leg of the frog is pinched, the stimulus is received by receptors on the skin that set up a sensory impulse. This impulse is carried to the spinal cord through the dorsal sensory root of a spinal nerve. The spinal cord then transforms the sensory impulse into a motor impulse. This impulse is then transmitted to the leg muscles. The muscles on receiving the impulse contract and the leg is withdrawn to avoid the stimulus. So, the correct option is 'simple reflex'.

Prolactin (PRL) is a hormone that stimulates milk production. Prolactin also plays an essential role in metabolism, regulation of the immune system, and pancreatic development.

Prolactin (also called as luteotrophic) hormone is associated with lactation (secretion of milk from the mammary gland). It is a hormone released by the pituitary gland that stimulates breast development and milk production in women. Therefore, to yield more milk cow is injected with prolactin hormone. 

Colostrum is a milky fluid that comes from the breasts of humans, cows, and other mammals the first few days after giving birth, before true milk appears. It contains proteins, carbohydrates, fats, vitamins, minerals and proteins (antibodies) that fight disease-causing agents such as bacteria and viruses. Antibody levels in colostrums can be 100 times higher than levels in regular cow’s milk.

Chameleons camouflage themselves in a variety of different ways but most famously by changing the colour and pattern of their skin. Most chameleons can change colour and they do this by expanding or contracting cells in their skin that contain different pigments. They can blend into their surroundings by altering the colour of their skin to match the background. Chamaeleon (girgit) shows protective colouration with its surrounding e.g., twig. 

Imprinting is defined as a learning process in which an offspring establishes species specific behaviour patterns along with recognition and attraction towards individuals of own species and even certain specific individuals (like parents). This process is classified as phase sensitive learning independent of external behaviour or other characteristics. In case of salmons, it has been theorized by Wisby and Hasler that they imprint on the unique odour of the natal water and as adults follow the same odour cues to their birth homes for spawning. Hence the correct answer is 'Imprinting'.   

Colostrum (also called as first milk) is the thin yellowish fluid secreted by the mammary glands at the time of parturition and which precedes the production of true milk. It provides a nursing infant with essential nutrients and infection-fighting antibodies (called as immunoglobulin) to protect the newborn against disease. IgA is the major immunoglobulin in colostrum. It protects from inhaled and ingested pathogens.

1. During mating, a male generally shows agressive behaviour as a form of superiority over other fellow males.
   2. Pheromones are used as a form of communication between two mating species.
   3. A male generally marks it's territory inorder to avoid anymore competition for mating.
   4. Visual communication is primarly used to locate and identify the mating partner.
   So, the correct option is 'Search image'.

So the correct answer is 'instinctual'.

Fish are given food at the same time as a tap on their glass bowl and soon learn to approach when a tap sounds even in the absence of food - it is an example of Classical conditioning.

A form of learning that occurs during a brief genetically determined critical period shortly after birth is called as imprinting. Habituation occurs throughout the life where individual learn to ignore the irrelevant stimuli. Reflex is a response to external or internal stimuli experienced throughout the life. Instinct and dominance are innate behaviours. The correct answer is D.

Because archegonia of pteris secrete a chemical malic acid which attracts only sperms of Pter!s thermostatically.

A form of learning that occurs during a brief genetically determined critical period shortly after birth is called as imprinting. Salmon learned, shortly after birth, about their birth place as they found themselves there just after birth. This makes them recognize the place and go there for breeding. Conditioned is also a learned response in which stimulus becomes associated with a consequence. Habituation is the most complicated form of learned behavior and includes applying something already learned to a new situation without a period of trial and error. The reasoning is making the concept of cause and effect in particular context. Thus, the correct answer is option E.

Circadian rhythm or diurnal rhythm is any 24 hour  periodicity in the behaviour or physiology of animals or  plants .Examples are sleep /activity cycle in many  animals and the growth movements of plants. Circadian  rhythms are generally controlled by biological clocks.

All flightless  birds belong to the super -order Ratitae e.g. Emu, Panguin, Rhea, win, Moa, Cassowary .

Sea cows (Rhytina) belong to order Sirenia of mammals. Presence of blubber and few hairs are characters of order sirenia. 

Bed bug ,sand fly silk worn are placed in tracheate  group of Arthropoda because they have trachae for  respiration Embryonic development of echinoderms shows a number of similarities with those of chordates .

The yellow-coloured milk secreted by cattle soon after the birth of a calf is called as colustrum. Colostrum contains antibodies to protect the newborn against disease. Colostrum is known to contain immune cells (as lymphocytes) and many antibodies such as IgA, IgG and IgM. However, the most abundant immunoglobulin in colostrum is IgA.

The yellow-coloured milk secreted by cattle soon after the birth of a calf is called as colostrum. It is rich in antibodies that confer passive immunity to the newborn

An organism is said to behave altruistically when its behaviour benefits other organisms, at a cost to itself. The costs and benefits are measured in terms of reproductive fitness, or expected number of offspring. So by behaving altruistically, an organism reduces the number of offspring it is likely to produce itself, but boosts the number that other organisms are likely to produce. 

A liger is a result of breeding a male lion to a tigress. A tigon is a result of breeding a male tiger to a lioness. Since lions and tigers do not exist in the same areas, this is not something that happens in the wild.

Tendrils is a modification in cucumber that helps the plant to climb higher and higher. These are skinny, wire-like structures along the plants stem. It also helps in grasping in cucumber. These tendrils are the modification of axillary buds located at the axial part of the leaf.

The orchid family (Orchidaceae) is subdivided into 5 subfamilies, 22 tribes and 70 subtribes and 850 genera are informal as alliances.

Most bats use frequencies in the range 20-80 kHz, only a few bats use frequencies less than 20 kHz.

Here the food chain be :
Grass Grasshopper Frog Snake Eagle The organism which occurs at the highest trophic level in the food chain will have the maximum concentration of harrnful chemicals in its body. since, eagle occurs atthe highest trophic level, therefore, it will have the maximum concentration of harrnful chemicals in its body.

Instinct is a kind of behaviour which does not involve any prior learning and is inherent and automatic. Thus, the loss of sensitivity to unimportant stimuli is a natural act which is instinctive in nature. For example, dancing of honeybees in the direction of food, animal fighting and courtship behaviour are are instinct behaviour. 

A form of learning that occurs during a brief genetically determined critical period shortly after birth is called as imprinting. Instinct is an inborn behaviour characteristic to a species and is often a response to specific environmental stimuli. Conditioning is also a learned response in which stimulus becomes associated with a consequence. Habituation is the most complicated form of learned behavior and includes applying something already learned to a new situation without a period of trial and error. Reasoning is making concept about cause and effect in particular context. Because the chicks learnt to follow mother goose and mother hen just after birth; it is imprinting. 

Imprinting is a form of learning that occurs during a brief genetically determined critical period shortly after birth. Habituation is the most complicated form of learned behavior and includes applying something already learned to a new situation without a period of trial and error. The reasoning is making the concept of cause and effect in particular context. Reflex and dominance occur during a late phase of life. 

Both habituation and imprinting are simple learned behaviours. Both are non associative learning process which means not associated with any reward or punishment. In habituation, the animal becomes habituated to the specific type of stimulus after repeated exposure. In imprinting, the learned behaviour occurs at a particular stage of maturation process in life. It mostly occurs in early stage of life of animals. Like the animal first recognizes the mother. This behaviour helps the animal in their survival in young age. 

Behaviour of organisms which belong to the same species can be seen in periodical cicadas that emerge the same year. The nymphs of periodical cicadas develop underground for 13 to 17years and live on juices from plant roots. After this period, they emerge from the soil and molt into winged adults. There are seven species of periodical cicadas four with 13-year life cycles and three with 17-year cycles. Each species of the periodical cicada has a distinctive song.

A form of learning that occurs during a brief genetically determined critical period shortly after birth is called as imprinting. Because the chicks learnt to follow mother goose and mother hen just after birth; it is imprinting. If they were exposed to mother pig shortly after hatching, they would exhibit pig like behavoiur.

Batesian mimicry refers to the resemblance of a harmless or palatable species with that of a dangerous or unpalatable one to make predators avoid them. A more common and distinct poisonous species present in the same area as mimic become familiar to predators of mimic and thereby increase the effectiveness of mimicry. Competition between mimic and poisonous species would harm either of them while mimicry is an adaptation for the protection of mimic. Thus, the correct answer is option C.

Bats are nocturnal flying mammals which do not employ eyesight for location of their path. food place of rest etc. They produce high frequency sound which produces echoes after striking various objects on the principle of sonar. Echoes are then analysed by bats to know their path.  

• Instinct is the natural force that causes a person or animal to behave in a particular way without thinking or learning about it.
  
• In almost every species of animals, caring for offsprings until they are mature enough is seen. 
  

Instinct is an innate, typically fixed pattern of behaviour in animals in response to certain stimuli. An instinct is something that doesn't need to learn and it happens naturally, without even thinking about it and so is the simplest form of learned behaviour. 

Colostrum is produced in the initial secretions of the mammary gland following the birth of offspring. Colostrum is most commonly distinguished from whole milk because it contains high concentrations of immunoglobulins (Ig), otherwise known as antibodies. Antibodies are proteins which function to identify and destroy disease-causing pathogens in livestock. The primary immunoglobulin in cow colostrum and milk is IgG, whereas the primary immunoglobulin in human milk is IgA. Colostrum is also a vital source of growth factors and nutritional elements such as protein, fat, milk sugar, vitamins and minerals.