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Classified in Biology
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Classified in Biology
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Classified in Biology
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Unicellular living organisms perform nutrition by exchanging substances directly with their surrounding environment. Nutrients and oxygen enter the cell through a plasma membrane, through which waste is also expelled.
Multicellular living organisms, such as human beings, have most cells that do not come into direct contact with the outside world and cannot exchange substances with it directly. The nutrition function is performed through the joint action of different systems that act as intermediaries between the outside world and cells.
The digestive
... Continue reading "Human Nutrition: Body Systems and Digestion Process" »Classified in Biology
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The spinal bulb is the extension of the medulla. It contains gray matter surrounded by white matter. Ascending neural pathways pass through the spinal bulb. They come from the medulla and provide information to the brain. The right side of the brain receives information from the left side of the body, and the right side receives information from the left. The movement of the right part of the body is controlled by the left side of the brain (and vice versa). It regulates several body functions, such as heartbeat, blood pressure, and breathing.
The brain stem is located between the spinal bulb and the brain, below the thalamus, and covers several areas of the brain. It regulates sleep, visual and auditory reflexes, and blood
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The primordial soup hypothesis is incapable of explaining the origin of life because the early atmosphere wasn't composed of the gases described by Oparin and Haldane. Also, we know that in the early atmosphere, there was no ozone layer, so it would make the first molecules very unstable because of UV radiation. The hypothesis was supported by the Miller-Urey experiment, which consisted of the following: a mixture of gases was put in a container, and high-voltage electric shocks were applied. Then, gases were condensed in another container, simulating the primitive ocean. Finally, several organic compounds were found in that simulated "primordial soup," including amino acids. As an alternative to the primordial... Continue reading "Origin of Life and Evolution: Theories and Evidence" »
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Every living cell needs energy. In humans, our cells need energy for:
All of this energy comes from the food that we eat. The food is digested (broken down) and absorbed from the intestine into the blood. Then, the blood goes to the body, and the cells take the nutrients.
Most of the time, our cells release energy from glucose by combining it with oxygen.
Aerobic respiration involves chemical reactions in cells that use oxygen to break down nutrient molecules to release energy.
glucose + oxygen → carbon dioxide + water
Anaerobic respiration involves chemical reactions in cells... Continue reading "Cellular Respiration: Aerobic vs. Anaerobic Processes" »
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Organism: A living thing made up of cells.
Cell: The smallest living part of a living thing.
Unicellular: Single-celled organisms.
Multicellular: Organisms made of many cells.
Compound Microscope: Combines two lenses to magnify objects.
Light Microscope: Uses light to view an object.
Resolving Power: The ability of a microscope to focus on two objects or details that are close together.
Magnification Power: The ability of a microscope to make an object appear larger.
Eyepiece: The lens you look through to magnify... Continue reading "Exploring the Microscopic World: Cells, Organelles, and Cellular Processes" »
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Human reproduction is sexual and has two key characteristics:
Humans have two types of gametes: sperm (men) and ova (women).
During the reproductive life of a human being, there are three main stages:
Puberty begins in men with the first ejaculation (spermarche) and in women with the first menstruation (menarche). This is due to the increased secretion of pituitary hormones: Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH), which stimulate gamete production.
Puberty typically begins when girls are 10-13 years old and boys 12-14. It lasts
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Mutations are alterations to a DNA sequence that occur when a gene is damaged or changed, altering the genetic message. These mutations can have varying effects on health, depending on their location and whether they alter essential protein functions.
Mutations can occur at three levels:
Mutations can be of different types:
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The cephalic phase initiates digestion before food even reaches the stomach. Sensory cues like taste, smell, or even the thought of food trigger the central nervous system to stimulate gastric juice production.
Once food enters the stomach, receptors signal the brain, which in turn promotes further gastric juice secretion to break down the ingested food.
As food moves into the duodenum, receptors detect its presence and signal the brain to increase the production of digestive juices for further processing.
When the duodenum is full, the enterogastric reflex is activated, causing the pyloric sphincter to close and regulate the passage of chyme from the stomach to the... Continue reading "Digestive System Processes: A Comprehensive Guide" »
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