|Topics||Cell Division, Comets, Conduction, Consumers, Exoskeleton, Large Intestine, Light Waves, Pulmonary Artery & Vein, Reproduction, Secondary Consumers|
Cell division is the process by which cells replicate genetic material in the nucleus. Cell division consists of several phases:
|interphase||chromosomes replicate into chromatids and the cell grows|
|prophase||chromatids pair up|
|metaphase||paired chromatids move to opposite sides of the cell|
|anaphase||cell elongates and nucleus begins to separate|
|telophase||separation of nucleus is complete resulting in two new nuclei|
|cytokinesis||cytoplasm and cell membranes complete their separation resulting in two separate cells|
A comet is a loose collection of ice, dust, and small rocky particles that, in contrast to an asteroid, has an extended atmosphere surrounding the center. When passing close to the Sun, this atmosphere warms and begins to release gases forming a visible coma or tail.
Heat is always transferred from warmer to cooler environments and conduction is the simplest way this transfer can occur. It is accomplished through direct contact between materials and materials like metals that transfer heat efficiently are called conductors while those that conduct heat poorly, such as plastic, are called insulators.
Most animals consume other organisms to survive. Consumers (heterotrophs) are divided into three types, primary, secondary, and tertiary, based on their place in the food chain.
An exoskeleton (external skeleton) is common in arthropods like insects, spiders, and crustaceans.
The large intestine (colon) follows the small intestine and processes the physical waste produced by digestion, absorbing water and minerials that remain back into the body. Solid waste is then stored in the rectum while liquid waste is stored in the bladder.
Unlike mechanical sound waves that require a physical medium for propagation, light waves are electromagnetic and can travel through empty space. Light waves are also much faster, travelling at 186,000 m/s vs. 343 m/s for sound waves.
The two largest veins in the body, the venae cavae, pass blood to the right ventricle which pumps the blood to the lungs through the pulmonary artery. Blood picks up oxygen in the lungs and returns it to the left atrium via the pulmonary vein.
During intercourse, the penis ejaculates sperm, produced in the testes, into the vagina. Some of the sperm makes their way to the uterus where, if they encounter an egg to fertilize, unite with the ovum to form a fertilized egg or zygote. The zygote then may implant in the uterus and eventually develop into a fetus.
Secondary consumers (carnivores) subsist mainly on primary consumers. Omnivores are secondary consumers that also eat producers. Examples are rats, fish, and chickens.