Biology Test - 43

The correct answer isScrotum.

Scrotum:

• The testesare situatedoutside the abdominal cavitywithin a pouchcalled thescrotum.
• The scrotumhelpsinmaintaining the lowtemperatureofthetestes (2–2.5 °C lower than the normal internal body temperature)necessary for spermatogenesis.

Testicular Lobules:

• Each testishas about250 compartmentscalledtesticular lobules.

Glands:

• A gland isan organthatproduces and releasessubstances that performaspecific functionin the body.
• Two typesof Glands-Endocrine, Exocrine.

Seminiferous Tubules:

• Seminiferous tubules arelocated in the testicles.
• Sperms are producedinSeminiferous Tubules.

The first Human hormone product by Recombinant DNA technology is insulin.

• The firstgenetically engineered insulinobtained by recombinant DNA technology with the help of E-Coli was developed by the American firm, Eli-Lilly on 5 July 1983.
• Insulinis used for diabetes.
• Insulinconsists of two short polypeptide chains: chain A and chain B, that are linked together by disulfide bridges.
• Eli Lillyan American company prepared two DNA sequences corresponding to A and B, chains of human insulin, and introduced them in plasmids of E. coli to produce insulin chains.
• Chains A and B were produced separately, extracted, and combined by creating disulfide bonds to form humaninsulin.

Therefore the first Human hormone product by Recombinant DNA technology is insulin.

Ingenetic engineering, we can break the DNA molecule at two desired places with the help of endonuclease. And then insert it in another DNA molecule at the desired place. The new DNA molecule is calledrecombinant DNA.Genetic engineeringcan be used to improve the quality of human life.

The pseudostratified epithelium is a type of epithelium that, though comprising only a single layer of cells, has its cell nuclei positioned in a manner suggestive of stratified epithelia. As it rarely occurs as squamous or cuboidal epithelia, it is usually considered synonymous with the term pseudostratified columnar epithelium.

Azolla pinnata is a species of fern known by several common names, including feathered mosquito fern and water velvet. Azolla pinnata has been found as an important biofertilizer for paddy crops.

Rice farmers sometimes keep this plant in their paddies, because it generates valuable nitrogen via its symbiosis, Cyanobacteria. The plant can be grown in wet soil and then plowed under, generating a good amount of nitrogen-rich fertilizer.

A leopard and a lion in a forest/grassland exemplify competition where both the species are competing for the same resources.
A cuckoo laying egg in a crow's nest is brood parasitism where cuckoo is the parasitic bird that lays its egg in the nest of crow (host bird).
Fungi and root of a higher plant in mycorrhizae exemplify mutualism where both the species are benefitted. The fungi help the plant in the absorption of essential nutrients from the soil while the plant in turn provides the fungi with energy yielding carbohydrates.
A cattle egret and a cattle in a field exemplify commensalism where one species benefits and the other remains unaffected.
The egrets always forage close to where cattle are grazing because the cattle, as they move, stir up and flush out insects from the vegetation that otherwise might be difficult for the egrets to find and catch.

• Inspite of interspecific competition the competing species may co-exist by doing resource partitioning.
• In mutualism two organisms are equally benefitted.
• In predation one organism (Predator) eats the another one (Prey).
• In competition release there occurs dramatical increase in population of a less distributed species when its superior competitor is removed.

Plasmolysis occurs due toExosmosis.

Exosmosis is a process in which the water molecules move from higher concentration region of the cell to the lower concentration region of surroundings through the cell membrane. Due to this, the cell shrinks. This happens when a cell is kept in hypertonic solution, i.e., a solution with higher solute concentration. Exosmosis is also termed as plasmolysis.

The ability to replicate is one of the important properties of genetic material.

A molecule that can act as a genetic material must fulfill the following criteria:

• It should be able to generate its replica (Replication).
• It should chemically and structurally be stable.
• It should provide the scope for slow changes (mutation) that are required for evolution.
• It should be able to express itself in the form of 'Mendelian Characters’.

Rice, wheat, and potato all are C₃ plants but amaranth is only the C₄ plant because amaranth is found in tropical and subtropical regions, these plants show Kranz anatomy in which vascular bundles in leaves are surrounded by a layer of bundle sheath cells that contain a large number of chloroplasts i.e., dimorphic. The chloroplasts of bundle cells are larger in size and are arranged centripetally while the mesophyll cells have the normal type of chloroplasts.

The correct sequence of organs in the alimentary canal of cockroach starting from the mouth is:

Pharynx → Oesophagus → Crop → Gizzard → Ileum → Colon → Rectum

i. Foregut:The food particle is ingested with the help of the mouth which leads to a small tube-like structure called the pharynx. It leads to another tube-like structure which is quite large called the oesophagus. This opens into a large sac-like structure called crop (Here, the food is stored prior to digestion). This leads to a small cup-like structure present beneath it, known as the gizzard or proventriculus. A gizzard is lined by thick cuticular layer and inside this layer, six chitinous teeth-like structures are present, which helps in cutting, grinding and mastication of food. In fact, the whole foregut is lined by a cuticular layer. At the junction of foregut and midgut, there are 6-8 thread-like structures present called hepatic cecum which secretes digestive enzymes.

ii. Midgut:It is the coiled tube-like structure and it is the main site of digestion. At the junction of midgut and hindgut, 100-150 fine thread-like structures are present called malpighian tubules. They act as the excretory organ.

iii. Hindgut:Their hindgut is divided into three parts; a narrow Ileum, a broad colon and sac-like rectum. The digested food is then discharged from the rectum.