Model Answer Mid Term 2009 Preden

Cairo University – Department of Zoology

Mid-Term Exam of Zoology for Predentary Students March 2009 Time allowed 1 hour A) Physiology (5 Marks) 1} Write the scientific term of each of the following: 1) It is a hormone secreted from a cell into the extracellular space (fluid) and affects the neighboring cell. (paracrine hormone) 2) It receives signals from the higher centers of the brain, translates them and sends the appropriate messengers to the pituitary gland, which in turn secretes the necessary hormone. (hypothalmus) 3) It stimulates uterine contraction during childbirth and initiates the production of milk by the mammary glands i.e. ↑ milk secretion. (oxytocin) 4) Iodide (I¯) in food and drinking water is absorbed from the gastrointestinal tract into the blood, which are then actively transported into thyroid cells against concentration gradient. (iodide pump) 5) It is a hypocalcemic hormone and secreted from parafollicular cells of thyroid gland. (cacitonin) 6) It is the only hormone that directly decreases the blood glucose levels. (insulin) 7) Usually, it is more dangerous and less common where it represents 10% of the total diabetics. (type I or IDDM) 8) It secretes mineralocorticoids such as aldosterone. (zona glomerulosa) 9) A decrease in vascular volume (due to hemorrhage or Na+ & water loss) leads to a decrease in blood pressure or in blood flow to kidney. This increases renin secretion from the kidney. Renin acts to stimulate release of a large protein called angiotensinogen from the liver, which directly stimulates aldosterone secretion. (rennin-angiotensin system) 10) A hormone that is secreted by alpha cells (25%) of the islets of Langerhans. (glucagon) 2} Put right (√) or wrong (X) and correct the wrong statement: 1) During the absorption of fats: Monoglyecerides and fatty acids from the micelles enter the lacteals. 2) Transamination involves the transfer of the amino 1

The mucosal cells

group of an amino acid to a Keto acid which provides non the basis for the formation of essential amino acids. 3) Upon contact of food with the pyloric mucosa, it Gastrin

releases the gastric secretions. 4) The physiologically important

hormone

polysaccharides Starch or inulin

or glycogen include cellulose, dextrins, lactose and chitin. 5) The degree of inhibition by non-competitive

inhibitors is reduced by the number of substrate not molecule. 6) Copper is an activator of several enzymes and is zinc required for synthesis of the hormone insulin. 7) Glycolysis means the brakedown of glycogen to glycogenlysis reform glucose in the cells. 8) Trypsinogin is activated by HCl to active trypsin entrokinase that

splits

proteoses

and

peptones

into

small

polypeptides. 9) From the essential amino acids are methionine , phenylalanine alanine, arginine and tryptophan. 10) All reactions of the citric acid cycle occur in the

cytosol, mitochondria and require oxygen.

‫تزال‬

B) HISTOLOGY (5 Marks) 3} Correct the following statements: 1) Calcified cartilage found in trachea. (suprascapula) 2) Collagen type IV found in reticular fibres. (III) 3) Desmosomes prevent passage of materials between cells. (tight junction) 4) Osteoclasts are responsible for synthesis of bone matrix. (osteoblasts) 5) Bipolar neurons found in spinal ganglia. (pseudounipolar) 4} Complete the following statements:

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1)

Haversian

canals

are

connected

with

each

other

by

. . . .volkman′s canal . . . . . . . . . . . . . . . . . . . . 2) Mitochondria of muscle cells called . . .. .sarcosome . . . . . . . . 3) The distance between two successive Z-lines called . . . . ……… sarcomere………. 4) . .Lymphocyte . . is a blood leukocyte contains large spherical nucleus. 5) . . Oligodendrocyte. . . is responsible for myelination of axons of nerve cells in central nervous system. 6) Irregular dense fibrous connective tissue proper found in . . . dermis . . . . . . . . 7) Apical surface of epithelial cell in intestine contains . . . . . … microvilli. . . . while in skin contains . keratin . . . . . 8) . . . Goblet ... cell is an example of unicellular gland. 9) Pseudo-stratified non-ciliated columnar epithelium found in … lung…….. C) Cytology (5 Marks) 5} By labeled diagram ONLY illustrate the structure of the mitochondria. ‫الرسمه عليها البيانات التالية‬: Outer membrane Inner membrane Cristae Matrix DNA Ribosomes Granules Respiratory paticles

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6} Complete the following statements: 1) In prophase, the microtubules between the two pairs of centrioles are extended inside

the cytoplasm to form …spindle

fibers……… . 2) In the nuclear envelope of the nucleus, the nuclear pore and its annulus are called ……porosome (nuclear poe complex.. 3) In Amphioxus, cleavage is …holoblastic….. , where the entire zygote divides (division extends from the animal pole o the vegetative pole). 4) In

prophase 1, homologous chromosomes lie side-by-side in a

process called …synapsis……… 5) In oogenesis, the cells resulting from the growth phase are called ………primary oocyte…………

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