Biology Test 130

A typhlosole is an internal fold of the intestine or the intestinal wall. In earthworms, typhlosole is a dorsal flap of the intestine that runs along most of its length, effectively forming a tube within a tube, and increasing the absorption area by that of its inner surface.

The characteristic feature of the intestine between 26-35 segments is the presence of an internal median fold of the dorsal wall called typhlosole. This increases the effective area of absorption in the intestine.

Hence, the correct option is (A).

Intercalated discs are part of the sarcolemma and contain two structures important in cardiac muscle contraction: gap junctions and desmosomes. A gap junction forms channels between adjacent cardiac muscle fibers that allow the depolarizing current produced by cations to flow from one cardiac muscle cell to the next.

Hence, the correct option is (B).

Haemophilia is a rare disorder in which your blood doesn't clot normally because it lacks sufficient blood-clotting proteins (clotting factors). If you have hemophilia, you may bleed for a longer time after an injury than you would if your blood clotted normally. Small cuts usually aren't much of a problem.

Haemophilia is a sex-linked and recessive disorder. The abnormal gene responsible for Haemophilia is carried on the X chromosome. Males have one X chromosome and one Y chromosome.

Hence, the correct option is (B).

Cycas or Cycads provide fixed carbon and a stable environment to the cyanobacteria in exchange for fixed nitrogen. These cyanobacteria are endosymbionts, living within the roots of Cycads. Within the coralloid root is the cyanobacterial zone, which is the region inhabited by cyanobacteria.

Hence, the correct option is (A).

In 1873, the German zoologist Otto Bütschli published data from observations on nematodes. A few years later, he discovered and described mitosis based on those observations. The term "mitosis", coined by Walther Flemming in 1882, is derived from the Greek word μίτος (mitos, "warp thread").

Hence, the correct option is (B).

Pruning is cutting off the apical portion of branches to induce growth which in turn lowers the amount of auxin synthesized as shoot apex. The lowered auxin synthesis allows translocation of cytokinins to lateral bud stimulating cell division and growth of lateral branches.

Hence, the correct option is (D).

Hence, the correct option is (B).

Autogenic succession is commonly found where the established community in response to environmental conditions or other factors changes its habitat eventually destroying itself. It is a kind of self-destruction that is triggered by external factors.

Hence, the correct option is (A).

The pleural cavity also known as the pleural space is the thin fluid-filled space between the two pulmonary pleurae (known as visceral and parietal) of each lung. A pleura is a serous membrane that folds back onto itself to form a two-layered membranous pleural sac. The outer pleura (parietal pleura) is attached to the chest wall but is separated from it by the endothoracic fascia. The inner pleura (visceral pleura) covers the lungs and adjoining structures, including blood vessels, bronchi, and nerves. The pleural cavity can be viewed as a potential space because the two pleurae adhere to each other (through the thin film of serous fluid) under all normal conditions.

Hence, the correct option is (C).

The heart muscles line the myocardium, or middle layer of the heart walls, and are responsible for the contractile function of the cardiac pump. Composed of cardiomyocytes, the heart muscle has distinctive cellular and physiological features allowing it to generate force to maintain adequate tissue and organ perfusion throughout the entire body. Heart muscle makes up one of the earliest functioning embryonic organs that continues to contract and beat from development throughout a lifetime.

Hence, the correct option is (B).