Parasites are organisms that benefit from harming other organisms. The organism they profit from is usually called host. Many parasites have complex life cycles, where they need different hosts for different stages of their development. As an example, the cycle egg > snail host > mammal host is common for parasites of herbivorous mammals. Malaria is caused by single-celled parasites. These parasites go through two stages in their development. One stage is in the blood of mosquitoes, the other in the blood of humans.
Examples of this can also be found in the Cnidaria. These animals live in the sea or in freshwater and the structure of most is relatively simple. Some live as single animals, others form colonies. In a colony, many animals live together. Often, each animal in a colony is specialized, and needs the other animals of the colony to survive.
A well-known example where different generations have different forms is the jellyfish. It has two:
In a complete cycle, the offspring of a medusa will develop into a polyp, and the offspring of a polyp will be a medusa.
Sometimes the cycle is modified or incomplete. Anthozoa is a group of the Cnidaria which contains sea anemones and corals. In the anthozoa, there is only a polyp stage, and no medusa stage.
The box jellyfish form another small group in the Cnidaria. In the box jellyfish, the polyp transforms into the medusa. In some cases, only part of the polyp transforms, the part that is left regenerates to form a new polyp. People have also talked about the box jellyfish because many of them produce poison that is very effective, and that can be dangerous to humans.
In the stalked jellyfish, there is only one form, which has been interpreted as a sessile medusa.
Yucca
Yucca is a family of shrubs and trees, related to the agaves. There are between 40 and 50 different kinds of Yucca. All come from the hot and dry places in North and Central America, as well as the Caribbean.
They have a very special way of pollination. There is an animal, the Yucca moth, which does the pollination. It also lays its eggs in the plant. The larvae will eat some of the seeds, but not all of them.
In many parts of the world, yuccas are grown as ornamental flowers.
Herb
Herbs are plants that are grown either as a food (usually as a condiment), or because they have some use in treating diseases (or making them better), or for spiritual reasons (for example, their smell). Some herbs may act as an aphrodisiac.
The word herb comes from the Latin word "herba", meaning grass, green stalks, or blades. Botanists use the word to mean any plant with soft, succulent tissues. But many people use the word to mean only herbs with some economic value.
Herbs are small plants that have a fleshy or juicy stem when they are young. The stems of some herbs develop hard, woody tissue when they grow old.
Most herbs are perennials. This means that the tops of the plants die each growing season, but the roots remain alive and produce new plants year after year.
Some herbs are annuals. They live for only one growing season and must be raised from seed each year.
The leaves, stems, or seeds of herbs can be used fresh, or they can be dried for later use. Dried herbs can be pounded to a fine powder, placed in airtight containers, and then stored.
Some herbs are used in cooking to flavor foods. Others give scents to perfumes. Still others are used for medicines. Some herbs, such as balm and sage, are valued for their leaves. Saffron is picked for its buds and flowers. Fennel seeds are valuable in relishes and seasoning. Vanilla fruit pods yield vanilla flavoring. Ginseng is valued for its aromatic roots.
People often grow herbs in their gardens. Some people grow herb gardens for the patterned beds that they can create with these plants. Many other gardeners grow herbs for the flavor that the fresh or dried plants add to food.
Herb seeds and seedlings are inexpensive, and the plants grow easily. People who do not have enough outdoor space for herb beds can grow most kinds of herbs in containers.
Many kinds of herbs can also be grown indoors. The plants grow well with little care. Gardeners plant herbs in good soil that has been well-cultivated. They choose a sunny spot near a window.
Podcasting
Podcasting is a way to share information as digital audio files. People often subscribe, download, and share podcasts using a computer and listen to them on an MP3 player.
Many podcasts are similar to broadcast radio news or discussion programs. Some use other formats such as a continuing story, comedy show, lecture, or audiobook.
Podcasts can be found for almost anything. Radio shows, do it yourself projects, special interest groups, religious sermons, comedy sketches, cartoons, and just about anything else can be found. Once a podcast is found, it can be subscribed to like a magazine or newspaper and then downloaded. Once it is downloaded, it can be stored on an MP3 player to be listened to.
Podcasting has become so popular that many people who write for magazines or report news on television have also been putting out their own podcasts. Anyone can start a podcast and share their knowledge with the world with the help of different platforms that are currently available online.
Alexander Fleming
Sir Alexander Fleming (6 August 1881 – 11 March 1955) was a Scottish biologist and pharmacologist. His father Hugh, died at 59 when Alexander was only seven. He is best known for discovering the antibiotic substance penicillin in 1928. He shared Nobel Prize in Physiology or Medicine in 1945 for this discovery with Howard Walter Florey and Ernst Boris Chain. His accidental finding of penicillin in the year 1928 marked the start of today's antibiotics.
Fleming was a captain in the Royal Army Medical Corps during World War I. He saw many soldiers die of infection after being wounded, and after the war did research in bacteriology. After accidentally finding penicillin he studied ways to use it.
Fleming died of a heart attack in London. He was buried in St. Paul's cathedral.
Litter box
A litter box (sometimes called a sand box, a litter tray or a litter pan) is a place for cats and some other pets to use as a toilet. Litter boxes usually need to be cleaned regularly. Cats, for example, wish to have their box cleaned every two to three days. Some cats create litterboxes in places like playgrounds and sandpits. Litterboxes usually produce bad smells, which can be avoided by special litter. Many people buy a special kind of clay to fill the box, for this reason.
Playground
A playground is an area used by children to play in. They usually have equipment such as slides, swings and seesaws for children to play on. They are usually outside, but sometimes they are in a building. Having a playground can enhance your macadam surface and improve your kid’s time in the playground.
The equipment may be made of metal, wood or plastic. The ground beneath the equipment will not be hard in case a child falls. It may be a rubber floor, or there may be woodchips or sand.
Playgrounds give children a place for physical exercise. This helps them get and keep physical fitness and be strong and healthy. Daily exercise reduces the risks of obesity.
Woodstock Festival
The Woodstock Music and Art Festival was a rock music festival at 's 600 acre (2.4 km²) dairy farm in the town of Bethel, New York from 15–18 August 1969. It might be the most famous rock concert and festival ever held. For many, it showed the counterculture of the 1960s and the "hippie era".
Many of the most famous musicians at the time showed up during the rainy weekend, as can be seen in a 1970 movie, "Woodstock". Joni Mitchell's song "Woodstock", about the event, also became a major hit song for Crosby, Stills, Nash & Young. In recent years, a number of attempts were made to recreate it, but the original Woodstock festival of 1969 has proven to be legendary.