No. Denning bears, such as brown and black bears, often retire to their caves for the winter months, but they sleep lightly, and are often active, with females giving birth to cubs during the winter. They don’t technically hibernate during these months. Hibernation is when a species passes the winter in an inactive state, conserving their resources and energy until winter passes.
Bears are not true hibernators because their body temperature drops only a few degrees and they show only a moderate drop in their metabolism. Small animals with high metabolic rates such as rodents, hummingbirds, and bats are true hibernators: their body temperature drops almost to the level of the surroundings and they show little response to nature’s sights and sounds. These animals collect and eat a lot of high-calorie foods (such as nuts) to store calories to make it through the hibernation period.
When you get sick, part or all of your body is not working as it should. The cause of sickness can come from inside your body or from the outside world. Diseases that start on the inside are usually inherited in the genes that you receive from your parents, Which make up the master plan that determines how your body will grow and run. Abnormal development or functioning of different body systems is the cause of many chronic (long-lasting) diseases. Things in the outside world can cause sickness, too. Poisons in the environment can cause illnesses in people. Not eating the right foods, with their important nutrients, can also cause diseases. But the most common cause of sickness from the outside world is infectious agents. These agents are usually microscopic organisms (living things so small that they can only be seen with the help of microscopes) like bacteria and viruses, which we commonly refer to as germs.
Bacteria and viruses and other microscopic organisms live in the air, water, and soil that make up our world. They are on the things and people we touch and in the food we eat. Many of them are beneficial: bacteria are needed to make cheese, some bacteria help vegetables like peas and beans grow, and some bacteria clean the environment and enrich the soil by feeding on dead plants and animals. But there are other microscopic organisms that invade the bodies of plants and animals—and people—and cause diseases.
Both bravery and courage are acts of valour and imply a certain strength and fearlessness. There is, however, a subtle difference in meaning between the two words. Courage comes from the French word coeur, meaning heart. It is a quality of character that allows someone to carry through with a difficult premeditated plan of action.
Bravery, on the other hand, comes from the Spanish word bravado, meaning a single or spontaneous act of valour. It is not planned, but rather a kneejerk reaction that often occurs within a crisis.
As a matter of fact, yes! Researchers believe that regular contact with pets can reduce levels of stress and reduce blood pressure (the force of blood pushing against the walls of the arteries as the heart pumps out blood).
Pets offer stability, comfort, security, affection, and intimacy. Owning a dog also provides a great opportunity to get exercise and fresh air, since it will need to go for a walk every day.
Crocodilians—scaly, carnivorous reptiles that include crocodiles, alligators, caimans, and gharials—are descendents of the archosaurs who lived on Earth with the dinosaurs 200 years ago.
Today’s modern crocodiles are semi-aquatic predators that have remained relatively unchanged since the Triassic period. Besides birds, they are the dinosaurs’ closest living relatives.
Before portable cellular phones, people like police officers or taxi drivers communicated from their cars using two-way radios. All of the radios in one city transmitted signals via a large, central antenna located on top of a tall building. With all callers sharing one antenna, the number of calls that could be made at any one time was very limited.
Consumers, like you and me, had an old type of cell phone that was permanently attached to the car and powered by its battery. The first transportable cellular phones had their own battery packs that allowed owners to detach them from the car and carry them in a pouch. However, most weighed about 5 pounds (2.25 kilograms) and were not very practical when used this way.
Scientists believe that the solar system in about 4.6 billion years old. Earth and the rest of the solar system formed from a giant cloud of gas and dust. Gravity and rotational forces caused the cloud to flatten into a disc and much of the cloud’s mass to drift into the center. This material became the Sun. The leftover parts of the cloud formed small bodies called planetesimals.
These planetesimals collided with each other, gradually forming larger and larger bodies, some of which became the planets. This process took approximately 25 million years, according to scientific estimates.
A veil is a piece of cloth that is usually worn to hide a person’s hair or face. Women have worn veils since ancient times—mostly in Middle Eastern countries— primarily to keep men from looking at them. Many women of the Muslim faith still wear veils of some type when they are out in public. In some Muslim countries, only a woman’s eyes are allowed to show.
Although Westerners (people from North America and Western Europe) may find these veils symbolic of women’s restricted freedoms in many Muslim societies, Muslim women wear them to honor long-held traditions of modesty and to show respect for their religion and the men in their lives.
Because animals are unpredictable and because schools have rules, it is never okay to bring animals out in public without the permission of both a parent and teacher. Even if you have permission, these creatures—such as snakes, rabbits, hamsters, gerbils, lizards, frogs, and other small critters—should be contained in their habitats and handled very carefully. Sometimes in public animals are outside of their natural habitats because they play a role in helping humans.
Guide dogs (also called seeing-eye dogs) help the blind or visually impaired move around cities and neighborhoods. These dogs are trained to behave properly on public transportation, in restaurants, in stores, and in any other place their masters go. Other times people carry their dogs and cats in pet carriers to the vet, to the park, or on shopping trips. However, they must have the store’s permission to enter, since many businesses (like restaurants and supermarkets) do not allow pets or require them to be contained and/or on leashes.
The greenhouse effect was first described in theoretical terms by a Swedish researcher, Svante Arrhenius, in the late 1800s. However it wasn’t until the following century that Arrhenius’s theory was observed. In the 1930s, scientists realized that parts of the globe had warmed during the previous half-century.
Then in the early 1960s scientists discovered that the level of carbon dioxide in the atmosphere was rising. Researchers began to take an interest and found a strong relationship between the increasing levels of carbon dioxide and average global temperature.