Biology Test 147

Spindle fibers are microscopic protein structures that help divide genetic material during cell division and organize cellular components. Spindle fibers are formed from microtubules with many accessory proteins which help guide the process of genetic division. Hence, the correct option is (B).

The chromosomes become visible under a light microscope during prophase in mitosis.

Prophase is the first phase of mitosis, the process that separates the duplicated genetic material carried in the nucleus of a parent cell into two identical daughter cells. During prophase, the complex of DNA and proteins contained in the nucleus, known as chromatin, condenses.

Hence, the correct option is (A).

The male gametes of angiosperms consist of two sperm cells within a pollen grain or a pollen tube. They are derived from a single generative cell, which is formed as the smaller cell by unequal cell division in the microspore after meiosis.
Hence, the correct option is (A).

Normally the genes encoding resistance to antibiotics such as ampicillin, chloramphenicol, tetracycline, or kanamycin, etc., are considered useful selectable markers for Escherichia coli.

A selectable marker is a gene introduced into a cell, especially a bacterium or to cells in culture, that confers a trait suitable for artificial selection. They are a type of reporter gene used in laboratory microbiology, molecular biology, and genetic engineering to indicate the success of transfection or other procedure meant to introduce foreign DNA into a cell. Selectable markers are often antibiotic resistance genes.

Hence, the correct option is (C)

The appendix or vermiform appendix is a muscular structure attached to the large intestine in the human body. It is a narrow tube resembling a worm and is named after the Latin word "vermiform" which means ‘worm-shaped’. The appendix extends from the lower end of the cecum, a pouch-like structure in the large intestine. The diameter of the appendix usually ranges from 7 to 8 mm and its length ranges between 2 and 20 cm, with an average length of 9 cm. The appendix is usually located at the lower right side of the abdomen.

Hence, the correct option is (D).

Hypoglycemia occurs when your blood sugar (glucose) level falls too low. There are several reasons why this can happen; the most common is a side effect of drugs used to treat diabetes.
Hence, the correct option is (B).

The apical meristem is the growth region in plants found within the root tips and the tips of the new shoots and leaves. Apical meristem is one of three types of meristem, or tissue that can differentiate into different cell types. Meristem is the tissue in which growth occurs in plants.

Intercalary meristem is a type of meristematic tissue associated with the growth in length in the middle position, thus the name. In particular, it is made up of meristematic cells that divide mitotically in the stem at the base of nodes and leaf blades.
Hence, the correct option is (B).

In karyotype analysis, a silver stain can be used to identify the NOR. NORs can also be seen in nucleoli using silver stain, and that is being used to investigate cancerous changes. NORs can also be seen using antibodies directed against the protein UBF, which binds to NOR DNA. Hence, the correct option is (B).

In reverse osmosis, the pressure is exerted on the side with the concentrated solution to force the water molecules across the membrane to the fresh water side. If pressure greater than the osmotic pressure is applied to the high concentration the direction of water flow through the membrane can be reversed.

Hence, the correct option is (B).

Restriction endonucleases are called as molecular scissors. It is because of the special feature of these enzymes to cut at desired sites of DNA in the technique of genetic engineering. These enzymes are found in bacteria and archaea and provide a defense mechanism against invading viruses.
Hence, the correct option is (D).