SF4POST

💡 Red blood cells contain hemoglobin, a protein that binds to oxygen in the lungs and releases it to tissues throughout the body.

💡 A renewable resource is one that can be used repeatedly and is naturally replenished on a human timescale, like energy from the sun.

💡 Coca alkaloids, such as cocaine, are central nervous system stimulants. They work by increasing the levels of neurotransmitters like dopamine in the brain, leading to heightened alertness and euphoria.

💡 Mars appears red because its surface is covered in iron oxide, or rust, which gives the landscape a reddish hue.

💡 The chemical formula H2O represents one oxygen atom covalently bonded to two hydrogen atoms.

💡 In a series circuit, the current flows through a single path. If that path is broken by a burnt-out bulb, the current cannot flow to the other bulbs.

💡 Gravity is the attractive force between all objects with mass. The Sun’s immense gravitational pull keeps the planets in their elliptical orbits.

💡 During photosynthesis, plants use sunlight, water, and carbon dioxide to create glucose (their food) and release oxygen as a byproduct.

💡 The three most common states of matter on Earth are solid, liquid, and gas. Heat is a form of energy, not a state of matter.

💡 The skin is the body’s largest organ, making up about 15% of your total body weight. It serves as a protective barrier against the environment.