Biology Test - 21

Bile juice, Pancreatic juicesecreted by the organs plays an important role in the digestion of fats. Bile juiceis secretedby the liver.

• It does not contain any types of enzymes.
• The bile juice helps to make the food alkaline and break down the fat molecules.

Pancreatic juiceis secreted by thepancreas.

• It contains enzymes like amylase, trypsin,pancreatic lipase, nucleases,amylase,and lipase.
• Secretion of thePancreatic juice is regulated by the hormones secretin and cholecystokinin.

Lipaseis the digestive enzyme of fat.

Ptyalin is thedigestive enzyme of theSaliva.

Hydrochloric acidis produced naturally in the human stomach to help the digestion of food.

Before antibiotics, the first commercial antibacterial available was prontosil.

The first commercially available antibacterial was Prontosil, a sulfonamide developed by the German biochemist Gerhard Domagk.Prontosil was the first drug to successfully treat bacterial infections and the first of many sulfa drugs forerunners of antibiotics.

Enzymes are defined as proteins that behave as biological catalysts. Catalysts are those which enhance the rate of chemical reactions that itself is changed. The alimentary canal is simply a pathway through which food enters the body and excretes out with the help of the anus after the process of digestion.

An enzyme used for the hydrolysis of starch to convert it into sugars like maltose, lactose, sucrose, etc. is known as amylase. This enzyme helps to start the process of chemical digestion because it is existing in the saliva of humans and some other mammals. Lactase is an enzyme that converts lactose (a type of sugar that is present in milk and gives it sweetness). This enzyme is elicited by various organisms. It is found in the small intestine (brush border portion) of humans and distinct mammals. Lactase is important for the complete digestion of entire milk. Invertase is an enzyme that causes the breakdown of sucrose. Maltase is an enzyme that catalyzes the conversion of maltose into simple sugar i.e. glucose. This enzyme is located on the brush border of the small intestine that catalyzes the breakdown of the disaccharide maltose.

The substrate is defined as the molecules upon which enzymes work and enzymes convert the substrate into the product. The alimentary canal is a long tube about 9 meters that run from mouth to anus and include- the oesophagus, stomach, small intestine, and large intestine. Digestion that starts in the mouth, well before food enters the stomach.

At acidic or alkaline pH the bases become charged and their solubility in water decreasesis false about purine and pyrimidine bases.

Purines and pyrimidines are the nitrogen bases that hold DNA strands together through hydrogen bonds. The purines in DNA are adenine and guanine, the same as in RNA. The pyrimidines in DNA are cytosine and thymine; in RNA, they are cytosine and uracil.

The purines and pyrimidines are also hydrophobic and relatively insoluble in water at the near neutral pH of the cell. At acidic or alkaline pH the purines and pyrimidines become charged, and their solubility in water increases. Hydrophobic stacking interactions in which two or more bases are positioned with the planes of their rings parallel (similar to a stack of coins) represent one of two important modes of interaction between two bases. The stacking involves a combination of van der Waals and dipole-dipole interactions between the bases. These base-stacking interactions help to minimize contact with water and are very important in stabilizing the three-dimensional structure of nucleic acids, as described later.

Medulla Oblongata is thepart of the brain that controls the heart.

Human brain isthe central organ of the human nervous system.The brain can be divided into three basic units:the forebrain, the midbrain, and the hindbrain.

Fore-brain:

Theforebrainstructures includethe cerebrum, thalamus, hypothalamus, pituitary gland.Cerebral hemispheresmake up the uppermost portion of the brain and areinvolved in the sensory mechanisms, control of voluntary movements, such asspeech.Thethalamusis the main relay centrebetween themedulla oblongataand thecerebrum.Hypothalamusis an importantcontrol centre forsex drive,pleasure,pain, hunger,thirst,blood pressure, body temperature, and othervisceralfunctions.Hypothalamusproduceshormonesthat control the secretions of the anteriorpituitary gland, and italso producesoxytocin.

Mid-brain:

Themidbrainlies between thethalamusandpons.Midbrain serves important functions inmotor movement, particularly movements of the eye, and in auditory and visual processing.

Hind-brain:

There are three main parts of the hindbrain -pons, cerebellum, and medulla oblongata.

• Ponsregulate respiration.
• The cerebellumhelps withthe coordination and movement related to motor skills, especially involving the hands and feet.
• Medulla Oblongataplays an essential role inpassing messages between your spinal cord and brain.
• It's alsoessential for regulating your cardiovascular(Heart) and respiratory systems.

Ovaries:

• The ova (eggs) are producedin the ovaries. They arematured from folliclesthat arestoredin theovaries of the woman.
• The eggis latertransferred to the uterus through the fallopian tube for fertilization.

Fallopian Tube:

• The Fallopian Tube isabout 10-12 cm long and extends from the periphery of each ovary to the uterus.

Uterus:

• The uterus issingleand it is alsocalled the womb.
• Theshapeof theuterus is like an inverted pear.
• It issupportedbyligaments attached to the pelvic wall.

Labia:

• The Labia are theouter portion of the vulva, there are two pairs of labia.
• One beinglabia majora (larger)and thelabia minor (smaller)theyprotect the entrance to the reproductivesystem.

Animals can be categorised into three types on the basis of their symmetry - Asymmetrical, Radial symmetry Bilateral symmetry.

When any plane passing through the central axis of the body divides the organism into two identical halves, it is called radial symmetry.

Radial symmetry is exhibited by Coelenterates, ctenophores and echinoderms.

Asymmetrical - If any plane that passes through the centre does not divide them into equal halves, this type of body plan is called asymmetrical.

Example - Porifera (Sponges)

Bilateral symmetry - If the body can be divided into identical left and right halves in only one plane, this type of body plan is called bilateral symmetry.

Example - annelids, arthropods, etc.

Alveoli is the tiny part inside the lungs where the exchange of oxygen and carbon dioxide actually takes place. Each person has hundreds of millions of alveoli in their lungs. The Trachea (windpipe) is the main passage leading from your nose to the lungs. The trachea divides into two main Bronchi (tubes), one for each lung. The bronchi, in turn, subdivide further into bronchioles. The smallest section of the bronchi is called Bronchioles, at the end of which are the alveoli (plural of alveolus). Every few seconds, with each inhalation, air fills a large portion of the millions of alveoli. In a process called diffusion, oxygen moves from the alveoli to the blood through the capillaries (tiny blood vessels) lining the alveolar walls. Once in the bloodstream, oxygen gets picked up by the hemoglobin in red blood cells. This oxygen-rich blood then flows back to the heart, which pumps it through the arteries to oxygen-hungry tissues throughout the body. In the tiny capillaries of the body tissues, oxygen is freed from the hemoglobin and moves into the cells. Carbon dioxide, made by the cells as they do their work, moves out of the cells into the capillaries, where most of it dissolves in the plasma of the blood. Blood rich in carbon dioxide then returns to the heart via the veins. From the heart, this blood is pumped to the lungs, where carbon dioxide passes into the alveoli to be exhaled.

Myoglobin is a protein found in the muscle cells of animals. It functions as an oxygen-storage unit, providing oxygen to the working muscles.

Balbiani rings are the sites of RNA and protein synthesis.

In certain development stages the polytene chromosomes bear conspicuous swellings called chromosome puffs. The larger swellings are called Balbiani rings. In the region of a puff or Balbiani ring, the DNA strands uncoil, become active and produce number of copies of mRNA. The mRNAs may remain temporarily stored in the puff and they may undergo transcription to form proteins. Thus, Balbiani rings are the sites of RNA and protein synthesis.