Biology (Practice Test)

Adrenal cortex is derived from Mesoderm and Adrenal medulla is derived from Ectoderm.

Proterozoic era is the age of early life. Coenozoic era is the age of mammals, birds and angiosperms and Mesozoic era is the age of reptiles. 

Uracil base is found only in RNA and thymine base is found only in DNA whereas adenine, guanine and cytosine bases are common in both DNA and RNA. DNA contain deoxyribose sugar instead of ribose sugar in RNA. 

A condition in whcih body's internal environment remains relatively constant within limits is called homeostasis homeostatic mechanisms protects an animal's internal environment form harmful fluctuations. It enables animals to survive large flucuations in theri external environment by tempering changes in body fluids. 

Body symmetry is the similarly of parts in different regions and directions of the body. In radical symmetry a number of similar parts radiate out form a central axis. The body of the individual can be divided into equal halves by any plane passing through the centre from top to bottom. Ex. Some sponges (Sycon) f coelenterates (hydra, jelly fish) echinoderms (e.g., starfish). 

The Haversian canals, a characteristic feature of the mammalian bones, are present in the matrix. The Haversian canals are interconnected by transverse canals called Volkmann's canals. 

Cryptorchidism or undescended testis (UDT) is one of the most common pediatric disorders of the male endocrine glands and the most common genital disorder identified at birth.

Maurer's dots are observed in the erythrocytes of man infected by P. falciparum. It is characterized by the whole sole destructions of the patient's erythrocytes and the excretion of the liberated haemoglobin in the urine. This is called black water fever. 

200 secondary spermatocytes will be required to form 400 spermatozons.

Echinodermates are totally marine, triploblastic, unsegmented and coelomate. Coelom is enterocoel. Larval stage is bilateral and adult is radial in symmetry. In echinodermates short and stout spines are present on the aboral surface which are blunt, immovable and calcareous. 

Embryonic cells differenciate at an early stage and form an outer layer of cells, the ectoderm and an inner layer the endoderm. At the later stage the mesoderm is formed and these three germ layers give rise to all the tissues of the developing embryo. Kidney and ureter in Rana Tigrina is developed from mesodermal layer. 

Cochlea consists of three fluid filled chambers, the upper scala media, scala vestibule and scala media, which are separated by Reissner's membrane. 

Any food that contains fat causes the gallbladder to release bile. The higher the fat content of the food or meal, the more bile is released.

Lampbrush chromosomes are a special type of chromosomes found in amphibian oocytes. They are found during the prolonged diplotene stage of first meiotic division in primary oocytes of amphibians. 

The blood group which is a universal acceptor is AB because plasma from the AB blood type has no antibodies against the antigens of other types, it can be given to anyone without causing an immune reaction.

Cretinism is caused by the deficiency of thryoid hormone in infants and myxoedema is caused by the deficiency in adults. Graves disease or exophalmic goitre is caused by the hypersecretion of thyroid hormone. 

Primitive atmosphere chiefly consisting of methane, ammonia, water vapour, hydrogen gas and was reducing. Oxygen was absent in primitive atmosphere. Oxygen came as a result of photosynthesis in green plants. 

 The type of placenta found in human beings is metaiscoidal type. The early blastocyst is first of all covered with villi but later they disappear from its free surface, persisting on a small disc-shaped area, attached to the uterine wall.

Sarcolemma is a thin membrane sheath of the muscle fibre.

The Mesozoic Era lasted about 180 million years, and is divided into three periods, the Triassic, the Jurassic, and the Cretaceous. Each of these periods is divided into many epochs and ages. Mesozoic means "Middle Animal" and is sometimes called the age of reptiles. The term Mesozoic was coined John Phillips in 1840.

<span style="font-size:10.0pt;font-family:Arial;mso-fareast-font-family:"Times" new="" roman";mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa="">The key cells responsible for immunity in vertebrates are white blood cells called lymphocytes which arise from precursor (stem cells) cells in the bone marrow. B-lymphocytes or B-cells mature in bone marrow while T-lymphocyte or T-cell mature in thymus. 

The mucous amembrane of intestinal wall is a single layered eptithelium of tall columber cells with interspersed golbelt cells. Thee epithelial cells have microvilli. In between the villi the mucous membrane is profusely folded and the infolding form pit-like simple tubular intestinal glands or crypts of Leiberkuhn. These secrete the intestinal digestive juice called succus entericus.<o:p>
Rennin is component of gastric juice secreted from stomach. It secreted in form of inactive proenzyme called prorennin. It changes the soluble casein proein of milk into insoluble semifluid calcium paracaseinate.<o:p>Saliva is secreted from salivary glands. The saliva contain ptyalin (salivary amylase) in mammals. 

Epimorphosis is a form of development in segmented animals in which body segmentation  is completed before hatching. Formation of sperms for small clumps of cells can not be a case of epimorphosis. 

Wild ass is found in Gujarat.

Trocopherol, does not belong to vitamin B group tocopherol represents vitamin E which is also known as antisterility vitamin. It is fat soluble vitamin. Other three belong to vitamin B group. Riboflavin is vitamin B₂, cyanocobalamine is vitamin B₃. These are water soluble vitamins.