Integrated Questions on General Biology Quiz

Answer: from a higher concentration to a lower concentration

Diffusion is the constant movement of particles going along the concentration gradient, that is from a higher concentration to a lower concentration. The ultimate goal of diffusion is to achieve the state of equilibrium within the space in which the particles have diffused.

Answer: middle mediastinum

The middle mediastinum is where the human heart is found. It's borders include the sternum in front, the lungs and primary bronchi at the back, and the diaphragm below.

Answer: Citric Acid Cycle

Glycolysis, translation and lactic acid fermentation occur in the cytoplasm of the cell. Meanwhile, citric acid cycle, also known as the Kreb's cycle or the tricarboxylic acid cycle (TCA), occurs in the mitochondrial matrix.

Answer: Resting Membrane Potential

The resting membrane potential is maintained by integral proteins found across the plasma membrane that act as ion pumps. It is approximately -70 millivolts. During depolarization, where there is an influx of sodium ions (going inside the cell), the membrane potential becomes less negative. An action potential occurs when the threshold (usually +30 millivolts) is reached during depolarization. A nerve impulse is generated ONLY when the threshold is reached (presence of action potential).

Spatial summation is achieved upon stimulation of a cell at different points, while temporal summation is achieved upon multiple stimulation of a cell at the same point.

Answer: cardiac muscle

Cardiac muscles are striated muscles just like skeletal muscles. They can be sometimes binucleated, unlike skeletal and smooth muscles which are mononucleated. They are well-known for their intercalating disks, containing gap junctions where chemical and electrical transmission of substances occur to enable the heart to contract voluntarily.

Answer: zona pellucida

The zona pellucida is the layer found immediately after the oocyte in a matured Graafian follicle. Corona radiata are cells surrounding the oocyte within the zona pellucida. Cumulus oophorus are also cells surrounding both the oocyte and the antrum (cavity).

Answer: quaternary structure

The primary structure of a protein is the sequence of amino acids in a peptide chain, and is stabilized by the peptide bonds (bond between 2 amino acids).

The secondary structure of a protein can either be helices, sheets, or loops of the protein caused and stabilized by the hydrogen bonds of the functional groups of each amino acid.

The tertiary structure is the folded and the three-dimensional structure a protein that is stabilized by disulfide bonds, ionic bonds, hydrogen and hydrophilic bonds.

The quaternary structure of a protein is best described as a protein being constituted by two or more protein sub-units or tertiary structures.

Answer: Definitive host (where sexual reproduction occurs)

In parasitology, a definitive host is where the parasite's life cycle is in its sexual phase. The asexual phase of a parasite's life cycle occurs in the intermediate host. In this case, sexual phase of the Plasmodium's life occurs inside the Anopheles mosquito, making it the definitive host. The asexual phase of the Plasmodium's life occurs in humans, making us intermediate hosts.

Answer: malic acid

Cacti store carbon dioxide as malic acid. They try to conserve water (because water loss is serious in the desert) by closing their stomata while compromising the entrance of carbon dioxide. So to accommodate carbon dioxide, the stomata only opens at night and they are stored as malic acid in the absence of sunlight. During day time, carbon dioxide is released from malic acid to proceed with the process of photosynthesis.

Answer: X chromosome

Turner's syndrome or gonadal dysgenesis do not develop mature and functional testes or ovaries because its sex chromosome is only X (or Xo). A Y-chromosome is needed to develop functional testes, while a pair of X (or XX) is needed to develop functional ovaries.