Listen to the conversation about joining a gym to practise and improve your listening skills. Do the preparation task first. Then listen to the audio and do the exercises. Preparation Transcript Task 1 Task 2
Chatting about a series
Listen to two friends chatting about a television series to practise and improve your listening skills. Do the preparation task first. Then listen to the audio and do the exercises. Preparation Transcript Task 1 Task 2
Leaving a message
Do the preparation task first. Then listen to the audio and do the exercises. Listen to someone leaving a message to practise and improve your listening skills. Preparation Transcript Task 1 Task 2
Meeting other students
Listen to a group of new students meeting for the first time to practise and improve your listening skills. Do the preparation task first. Then listen to the audio and do the exercises. Preparation Transcript Task 1 Task 2
Biological Macromolecules and Their Subunits
The atoms of four elements make up roughly 99 percent of the mass of most cells: hydrogen, nitrogen, carbon, and oxygen. With only a few exceptions, molecules that contain carbon atoms are called organic compounds. There are millions of different organic compounds. Nearly all organic compounds contain hydrogen as well as carbon, and most of […]
Bonding and the Shape of Organic Molecules
Early scientists defined organic compounds as compounds that originate from living things. In 1828, however, the German chemist Friedrich Wohler (1800–1882) made an organic compound called urea, CO(NH2)2, out of aninorganic compound called ammonium cyanate, NH4CN. Urea is found in the urine of mammals. This was the first time in history that a compound normally […]
Atoms and Bonding
Living things are unique among all forms of matter.Unlike non-living things, all living things — from single-celled organisms such as the Euglena in Figure 1.1 to multicelled organisms such as whales and redwood trees — interact with and manipulate matter and energy. For example, all cells take in essential substances such as oxygen, water, and […]
TRANSPORT IN PLANTS AND ANIMALS
IntroductionThe movement of materials within the body tissues or between tissues in multicellular organisms like high plants and animals occurs in transport systems. In unicellular or low plants and animals, such movement is by the transport mechanisms of molecules within a transport medium by diffusion, osmosis, active transport and mass flow, among others.In multicellular animals, […]
VITAL FUNCTIONS IN ANIMALS
ANIMAL NUTRITION Nutrition in animals is heterotrophic. This means that animals feed on other living things. Animals can be classified according to their nutrition function: herbivores (plant eaters), carnivores (eat other animals), omnivores (eat animals and plants) and saprophytic (feed on decaying organic matter). In order to perform the vital function of nutrition, animals have different systems: digestive, respiratory, circulatory and excretory. Digestive system The digestive […]