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(C) It causes increased sweating

A. False BMR falls due to a decrease in resting thyroid activity. 

B. True Partly due to increased thermoregulatory blood flow. 

C. False Urinary output is usually reduced due to increased water loss by extrarenal routes. 

D. True Daily secretion of sweat may rise to several litres. 

E. True Due mainly to the improved ability to dissipate heat.

A. True Due to stimulation of peripheral chemoreceptors by hypoxia. 

B. False Bicarbonate is lost in the urine to compensate for the respiratory alkalosis. 

C. False Loss of appetite (anorexia) is a common complaint in mountain climbers. 

D. False Exercise tolerance is reduced by the decreased ability to deliver O₂ to the blood. 

E. True Due to an increased erythropoietin level.

Vesicles store and transport materials with the cell. Some of these materials are transported to other organelles, other materials are secreted from the cell.
Examples of vesicles include secretory vesicles, transport vesicles, synaptic vesicles, and lysosomes.
Vacuoles are membrane-bound organelles that can have secretory, excretory and storage functions. They are usually larger than vesicles.

Fructose - (C₆H₁₂O₆) or fruit sugar, is a simple monosaccharide found in many plants . Most fructose can be commercially produced as a component of high fructose corn syrup. It is used in food manufacturing because it is cheap and effective as a flavoring and preservative.

Respiratory acidosis is that in which the blood pH is low due to increased retention of carbon dioxide caused by the lowering of the respiratory frequency or by pulmonary diseases that impair the gas exchange. So the cause of the respiratory acidosis is the pulmonary respiration. Metabolic acidosis is that in which the blood pH is low not due to the pulmonary retention of carbon dioxide but due to metabolic disturbances. Some metabolic disturbances result in liberation in the blood of nonvolatile acids that release hydrogen ions lowering the blood pH (e.g., diabetic ketoacidosis).

Respiratory alkalosis is that in which the pH is high due to increased expelling of carbon dioxide caused by elevated respiratory frequency. Metabolic alkalosis is the alkalosis caused by metabolic disturbances that increase the concentration of bases (alkalis) in the blood.

In animals that do not present the circulatory system the transport of substances occurs by cell to cell diffusion.

The blood is a fundamental means of substance transport for larger animals since in these animals there are tissues distant from each other and from the environment thus making diffusion impossible.

Since amphibian larvae are aquatic they excrete ammonia. The terrestrial adult excretes urea. 

Urea is more water-soluble than uric acid (an almost insoluble substance). Urea is also more toxic. Both however are less toxic than ammonia.

Some invertebrates, chondrichthian fishes, adult amphibians and mammals are ureotelic. Reptiles, birds and most arthropods are uricotelic.

Human beings excrete mainly urea eliminated with the urine.

Placental animals, including embryos, excrete urea. In the adult placental mammal urea is excreted through the urine. In embryos the molecule passes to the mother’s blood through the placenta and it is excreted in the mother’s urine.

The main nitrogen wastes excreted by living beings are ammonia, uric acid and urea. Living beings that secrete ammonia are known as ammoniotelic. Creatures that secrete uric acid are known as uricotelic. Organisms that secrete urea are called ureotelic.

A. True The autosomes are similar for males and females. 

B. False Half would receive the normal autosome. 

C. False Such genes are commonly transmitted. 

D. False If so, it would not be a dominant disorder. 

E. False Carriers of a dominant character exhibit the disease.

A. False Blood pressure rises due to reflex stimulation of the heart and peripheral vasoconstriction. 

B. True Accumulation of CO₂ is mainly responsible for the reflex cardiovascular and respiratory responses. 

C. True Deoxygenated haemoglobin appears in the arterial blood. 

D. False Respiratory effort increases with chemoreceptor stimulation. 

E. True Part of the generalized sympathetic response to stress.

The chemoreceptors that participate in the ventilation control are structures that collect information about the acidity and alkalinity of the blood. The information is then transmitted by nervous fibers to the respiratory center located within the medulla. The center then commands the respiratory muscles to compensate the abnormal pH.

There are central and peripheral chemoreceptors. Peripheral chemoreceptors of pH, carbon dioxide partial pressure and oxygen partial pressure are located in the walls of the aorta and of the carotid arteries. Central chemoreceptors that get pH information are located within the medulla in the respiratory center. (The pulmonary ventilation is also controlled by receptors that receive pH information from the cerebrospinal fluid.)

Not all animals have a circulatory system.

Poriferans, cnidarians, platyhelminthes and nematodes (in these there are the pseudocoelom fluid but no vessels) are avascular animals. Echinoderms do not have true circulatory systems either.

A closed circulatory system is one in which blood circulates only inside blood vessels. For this reason the blood pressure is higher in animals with closed circulatory system. The cellularity of the blood is also higher with many specific blood cells. 

The closed circulatory system is a feature of annelids, cephalopod molluscs and vertebrates.

Cephalopod molluscs, like octopuses and squids, have a closed circulatory system with blood pumped under pressure flowing within vessels. Bivalve molluscs, like mussels and oysters, have an open circulatory system (also known as lacunar circulatory system) where blood flows under low pressure since it falls in cavities of the body and does not only circulate within blood vessels. Molluscs with closed circulatory systems are larger, agile and can actively move; molluscs with open circulatory systems are smaller, slow and some are practically sessile.

Open circulatory system is the one in which blood does not circulate only inside blood vessels but it also falls in cavities that irrigate tissues. In the open circulatory system the blood pressure is low and generally the blood (called hemolymph) has low cellularity.

Arthropods, molluscs (the cephalopods are exception) and protochordates have open circulatory system.

The lymphatic system is a network of specialized valved vessels that drain interstitial fluid (lymph). The lymphatic system is also responsible for the transport of chylomicrons (vesicles that contain lipids) made after the absorption of fats by the intestinal epithelium.

In the way of the lymphatic vessels there are ganglial-like structures called lymph nodes that contain many cells of the immune system. These cells filter impurities and destroy microorganisms and cellular wastes. The lymphatic vessels drain to two major lymphatic vessels, the thoracic duct and the right lymphatic duct, that in their turns drain into tributary veins of the superior vena cava.

Nitrogen wastes are residuals derived from the degradation of proteins. They are made from chemical transformation of the amine group of amino acid molecules.

In reptiles and birds the excretory system is uricotelic since uric acid is insoluble, less toxic and suitable to be stored within the eggs where their embryos develop. 

A. False The abnormality is on the X chromosome. 

B. False Females are protected by the normal X chromosome. 

C. False Both can transmit a defective X chromosome. 

D. True Due to protection by a normal X chromosome. 

E. True Colour blindness is another example.

A. True But the side effects are likely to be worse than the disease. 

B. True Again side effects may be troublesome. 

C. False This paralyses skeletal muscles without inhibiting sweating. 

D. False The nerves responsible for sweating are cholinergic. 

E. True This is an effective therapy.

Varix means abnormal enlargement of veins. Varices occur when excessive pressure against the normal blood flux creates enlargement of the vein and thus insufficient functioning of its valves (venous insufficiency). 

Varices are more common in the veins of the inferior limbs since the fluid column above these vessels is higher. This is the reason why people that spend much time standing (e.g., surgeons) are more susceptible to varices. 

In general varices are not the apparent superficial veins that appear in the leg of varix patients. These apparent vessels are the consequences of internal varices (venous insufficiency) in the deep internal veins of the legs and they appear because the blood flux is diverted to superficial veins. (Popularly however apparent superficial veins are called varices.)

Circulation is the movement of substances like nutrients and gases within blood vessels and cavities throughout the organism.

The typical components of the closed circulatory system are the blood vessels within which blood circulates (arteries, veins and capillaries), a pumping organ (heart) and the blood or bloodlike fluid.

Excretion in Physiology is the process of elimination of metabolic wastes and other toxic substances from the body.

In vertebrates almost 70% of the carbon dioxide is transported by the blood in the form of bicarbonate, 25% bound to hemoglobin and 5% dissolved in the plasma.

A. True Adults are normally in nitrogen balance. 

B. True It exceeds intracellular fluid volume. 

C. False Both infants and adults have reticulocytes in the blood. 

D. False It is higher; the pressure gradient to cardiac output ratio is much greater. 

E. False They are relatively much larger.

Complete circulation is that in which there is no mixture of venous blood and arterial blood. Simple circulation is that in which the blood circulates only in one circuit (as opposed to the double circulation that have two circuits, the systemic circulation and the pulmonary circulation). In fishes the circulatory system is simple and complete.

The venous blood coming from the tissues enters the atrium and passes to the ventricle that then pumps the blood towards the gills. After oxygenation in the gills the arterial blood goes to the tissues. So the fish heart pumps venous blood.

The muscles of the legs, mainly the muscles of the calves, contract and compress the deep veins of the legs impelling the blood to the heart.

The plantar portion of the feet retains blood and when it is compressed against the ground it impels its blood volume and aids venous return.

The valves of the venous system are structures inside the veins that permit blood to flow only in the normal way (from the tissues to the heart) and forbid it to return in the reverse way in favor of gravity. The valves close when the pressure of the fluid column above (after, regarding normal flux) is higher than the fluid pressure before them. Valves are thus fundamental for the returning of blood to the heart.

Venous vessels are every blood vessel that carries blood from the tissues to the heart. Veins and venules are venous vessels. Venules are thin veins that are continuous to capillaries.

In general venous vessels carry venous blood. The pulmonary veins that carry blood from the lungs to the left atrium of the heart however contain arterial blood.

Double closed circulation, or closed circulation, is that in which the blood circulates through two associated and parallel vascular systems: one that carries blood to and takes blood from the peripheral tissues (the systemic circulation) and the other that carries blood to and takes blood from the tissues that perform gas exchange with the environment, e.g, the lungs (pulmonary circulation). Double circulation occurs in amphibians, reptiles, birds and mammals.

Simple closed circulation, or simple circulation, is the one in which the tissues that perform gas exchange are associated in series with the systemic circulation, as in fishes.

Heart contraction is independent from neuronal stimulus (although it can be modulated by the autonomous nervous system). In the heart there are pacemaker cells that trigger by themselves the action potentials that begin the muscle contraction. These cells are concentrated at two special points of the heart: the sinoatrial node (SA node) located in the superior portion of the right atrium and the atrioventricular node (AV node) located near the interatrial septum.

The action potentials generated by depolarization of the SA node cells propagate cell to cell throughout the atria producing the atrial contraction. The atrial depolarization also propagates to the AV node that then transmits the electric impulse to the ventricles through specialized conduction bundles of the interventricular septum (the bundle of His) and then to the Purkinje fibers of the ventricle walls causing ventricular contraction. (The atrial contraction precedes the ventricular contraction for blood to fill the ventricles before the ventricular contraction.)

The repolarization of the SA node makes the atria relax and then the ventricles relax too.

The amphibian circulation is double because it is composed of systemic and pulmonary circulations: respectively, heart-tissues-heart and heart-lungsheart. Since amphibians have only one ventricle in the heart, venous blood taken from the tissues and arterial blood coming from the lungs are mixed in the ventricle that then pumps the mixture back to the systemic and to the pulmonary circulations. The amphibian circulation is classified as incomplete because venous and arterial blood mix in the circuit.

The blood oxygenation in amphibians occurs also in the systemic circulation since their skin is a gas exchange organ. 

The amphibian heart has three heart chambers: two atria and one ventricle.

The heart chambers through which blood enters the heart are the atria. There are the right atrium and the left atrium.

The heart chambers through which the blood exits the heart are the ventricles. There are the right ventricle and the left ventricle.

The reptiles have double and incomplete circulation too, three heart chambers (two atria and one ventricle). The reptile heart however presents the beginning of a ventricular septation that partially separates a right and left region of the chamber. With the partial ventricular septation the mixture of arterial with venous blood in the reptile heart is less than in amphibians.

In the human fetal circulation there are two communications between arterial and venous blood characterizing an incomplete circulation. One of them is the oval foramen, an opening between the right and the left atria of the fetal heart. The other is the arterial duct, a short vessel connecting the pulmonary artery to the aorta. These communications close a few days after birth and so they are not present in the adult heart.

The fish heart is a tube made of two consecutive chambers: one atrium and one ventricle.

The bird and the mammalian hearts are divided into four chambers: right atrium, right ventricle, left atrium and left ventricle.

Birds and mammals are homeothermic, i.e., they control their body temperature. The four-chambered heart and the double circulation provide the supply of more oxygenated blood to the tissues making possible a higher metabolic rate (mainly cellular respiration rate). Part of the energy produced by the cellular respiration is used to maintain the body temperature.

Both. As biotechnology is a very wide area which deals with techniques of using a ‘natural’ organism (or its parts) as well as genetically modified organism to produce products and processes useful for mankind. A wine maker employs a strain of yeast to produce wine by fermentation (a natural phenomenon), while the molecular biologist has cloned gene for the antigen (that is used as vaccine) in an organism which allows the production of the antigen in large amount.

If the restriction enzymes would cut DNA at random sites instead of at specific sites, then the DNA fragments obtained will not have ‘sticky ends’. In the absence of sticky ends, construction of recombinant DNA molecule would not be possible.​

The experiment will not likely to be affected as recombinant DNA molecule is circular closed, with no free ends. Hence, it will not be a substrate for exonuclease enzyme which removes nucleotides from the free ends of DNA.

The experiment will not likely to be affected as recombinant DNA molecule is circular closed, with no free ends. Hence, it will not be a substrate for exonuclease enzyme which removes nucleotides from the free ends of DNA.

Hybridoma technique was first discovered by Kohler and Milstein.

(1) In summer season, transpiration rate is very high in plants. 

(2) To reduce the transpiration rate plants shed their leaves. 

(3) And some waste materials are also stored in leaves and removed by shedding of leaves. 

(4) Bark is the outer zone of plants, which contain phloem to transport food materials. 

(5) In the growing period cambium produces bark tissue. When new bark tissue is produced, the old bark is removed. 

(6) In this process the old and dead cells filled with waste materials are also removed.