Summary
Highlights
The human brain is an organ, which is a special group of tissues performing specific jobs. It controls most body activities through the nervous system, composed of the central nervous system (brain and spinal cord) and the peripheral nervous system (nerves throughout the body). The brain is protected by the skull and is responsible for thinking, dreaming, and imagining.
Reptiles are fascinating animals like snakes, turtles, crocodiles, and lizards. They are characterized by dry, waterproof scales, breathe oxygen with two lungs, and are cold-blooded, meaning they rely on external heat sources like sunlight to regulate their body temperature.
Pollination is the process by which flowers make seeds. Pollen, a fine yellow powder made in the stamen (male part), must be transferred to the pistil (female part). Pollinators like honeybees, butterflies, bats, hummingbirds, wasps, moths, ants, and beetles assist in moving pollen, enabling flowers to produce fruit and seeds for new plants.
The Earth's outer shell, called the crust, is made of constantly moving pieces. When these pieces move quickly, an earthquake can occur. Earthquakes start underground at the 'focus' and shake the ground, causing damage. The strongest shaking occurs at the 'epicenter,' directly above the focus. Earthquakes are measured and scored by seismographs, with higher scores indicating stronger earthquakes.
Plants have six main parts: roots, stems, leaves, flowers, fruit, and seeds. Roots anchor the plant and absorb water and nutrients. Stems support the plant and transport water and food. Leaves produce most of the plant's food using air, water, and sunlight. Flowers attract pollinators and develop into fruit. Fruit holds and protects the seeds, which are responsible for growing new plants through dispersal.
The heart is a muscular organ with four chambers: the right atrium, left atrium, right ventricle, and left ventricle. Its primary function is to pump blood throughout the body, delivering oxygen and nutrients. This process is part of the circulatory system, essential for maintaining health and strength.
Planets are spherical objects that orbit the sun. There are eight primary planets: Mercury, Venus, Earth, Mars (inner rocky planets), Jupiter, Saturn, Uranus, and Neptune (outer gas planets). Each planet has unique characteristics, such as Mercury being the smallest and hottest, Venus being Earth's twin, Jupiter being the largest with many moons, Saturn's icy rings, Uranus's tilt, and Neptune's extreme storms.
Sharks are a diverse type of fish, with over 440 species ranging from the large whale shark to the small dwarf lantern shark. Unlike most fish, sharks do not have bones; their skeletons are made of flexible cartilage. They use their numerous teeth to bite but swallow their prey whole. Sharks play a crucial role in balancing the ocean ecosystem, for example, by preying on herbivores that consume coral reefs. Unfortunately, human activities lead to the death of millions of sharks annually, highlighting the need for their protection.