Notes, summaries, assignments, exams, and exercises for Biology for Other courses

1. Interphase

The cell cycle begins with interphase, which lasts longer than mitosis. During this stage, the cell duplicates its components and DNA.

G1 Phase (5 hours)

Occurring after mitosis and before DNA synthesis, the cell increases in size and accumulates substances necessary for division. This stage includes the Restriction Point (R); if the cell does not pass this point, it enters the G0 phase (quiescent state, e.g., neurons). By the end of this phase, protein synthesis increases, histones are transported to the nucleus, and the number of centrioles and microtubules grows.

S Phase (6-8 hours)

During this phase, DNA replication occurs. Euchromatin is replicated first, followed by heterochromatin. Metabolic activity decreases, while histone...

Operation of the Eye

The eye functions through two primary mechanisms: regulating light intensity and focusing images.

Light Regulation

Excessive light can cause injury and hinder visual processing. The pupil regulates light intake by dilating or constricting via the muscles of the iris.

Focusing Images

To prevent blurry vision, the eye must focus images precisely on the retina. This is achieved by the lens (cristalline), which flattens to view distant objects and bulges for nearby ones. A healthy eye typically focuses between 15 cm and 65 m.

The image reaches the brain inverted, where it is corrected. Human vision is stereoscopic, allowing for 3D perception, depth estimation, and size recognition.

Taste

Taste captures information about diet through...

Sensory Receptors

Sensory receptors are specialized nerve cells that capture stimuli and transform them into nerve impulses. They include chemoreceptors, mechanoreceptors, photoreceptors, thermoreceptors, and nociceptors.

Interoreceptors

Interoreceptors, also called internal receptors, are located inside the body. They detect information from the internal organs and viscera.

Exteroreceptors

Exteroreceptors, also called external receptors, are located on the body surface. They recognize external stimuli such as light, sound, and temperature.

Vision

Vision resides in the eyes, which are complex organs specialized in receiving light stimuli.

Eyeball

The eyeball is spherical, and its walls are made of three layers: the sclera, the choroid, and the retina....

Cell Division Processes

Mitosis: Somatic Cell Replication

Mitosis is an equational division resulting in two identical daughter cells. This process covers the growth and repair throughout the life of organisms.

• Homologous chromosomes do not form pairs.
• Results in 2 identical daughter cells.
• Cells can undergo successive mitotic divisions.
• Occurs in somatic cells (all body cells, excluding germ cells).

Meiosis: Gamete and Spore Formation

Meiosis is the process of cell division that occurs in germ cells, resulting in genetically distinct reproductive cells (gametes or spores).

1. First Division: Reductional.
2. Second Division: Equational.

• Homologous chromosomes form pairs.
• Results in 4 daughter cells, genetically different from each other.
• Cells cannot undergo