THE INDIAN PUBLIC SCHOOL – CAMBRIDGE INTERNATIONAL BIOLOGY HANDOUT Name : Grade : VI - VII Organisms An organism is simply defined as any living thing, ranging from microscopic bacteria to large elephants and everything in between. Different types of plants and animals are found in different areas. E.g. deserts have camel and cacti as plants. Beaches show coconut trees and crabs. Fishes and other marine animals inhabit the sea. Characteristics of Living Organisms Plants are living things, but they do not appear to move like a dog or a pigeon. On the other hand, a car or a bus can move, yet we consider them as non-living. So there are certain characteristics that differentiate living from nonliving- 1. Living beings are made of cells. 2. Living beings obtain and use energy. 3. Living beings grow and develop. 4. Living beings reproduce. 5. Living beings adapt to their environment 6. Living beings respond to their environment or stimuli. Animal Adaptation Adaptation The presence of specific features or certain habits, which enable a plant or an animal to live in its surroundings, is called adaptation. Different animals are adapted to their surroundings in different ways. Eg: Fish have slippery scales on their bodies. These scales protect the fish and also help in easy movement through water. Habitats Surroundings The different surroundings or areas have different organisms that live in. E.g.: The deserts have camels, the mountains have goats and yak. Habitat The surrounding where living organisms survive is known as habitat. The organisms depend on their habitat for their food, water, air, shelter and other needs. Habitat means a dwelling place (a home). Several kinds of plants and animals may share the same habitat. Biotic Components The living components of a habitat are called biotic components. Eg: plants, animals Abiotic Components The non-living components of a habitat are called as abiotic components. E.g.: rocks, soil, air, water etc Terrestrial Habitats The plants and animals that live on land are said to live in terrestrial habitats. E.g.: forests, grasslands, deserts, coastal and mountain regions. Aquatic Habitats The habitats of plants and animals that live in water are called aquatic habitats. E.g.: ponds, swamps, lakes, rivers and oceans. Aquatic habitats could be fresh water (river, pond) or marine (sea) or even estuarine (delta of river meeting with the sea) How plants grow How plants grow and change? The different parts of a plant are shown in the picture. The main parts of most plants are roots, stem, leaf and flower. Roots of a plant are present under the ground. These roots give support to the plant. These carry water, minerals and nutrients from the soil for the plants. Roots grow underground. Stem of a plant is present above the ground. It also gives support to the plant. It also bears branches, leaves, fruits and flowers. It carries food and water to all parts of the plant. Stem is known as the back-bone of the plant. Leaf prepares food for the plant. Flower is the most beautiful part of a plant. It changes into fruit. Most of the plants bear flowers. Flowers are of different shapes, sizes and colors. Some flowers smell good. Some of the good smelling flowers are rose, jasmine, lotus, sunflower, apple flower. Flowers change into fruits. Fruits are juicy and tasty. Some fruits are apple, orange, mango, watermelon and peach. Fruits are very useful for us. They protect us from various diseases. We should eat plenty of fruits daily. Most fruits contain seeds inside them. Some of the fruits which contain seeds are mango, apple, orange, watermelon and papaya. Seeds are of different shapes and sizes. Plants grow from seeds. A baby plant is hidden inside a seed. Seeds also contain food for the baby plant. There are different kinds of seeds. A baby plants grows into a big plants. Look, how a seed grows into a plant. Human Organ System What is the digestive system? The digestive system is made up of the gastrointestinal tract—also called the GI tract or digestive tract— and the liver, pancreas, and gallbladder. The GI tract is a series of hollow organs joined in a long, twisting tube from the mouth to the anus. The hollow organs that make up the GI tract are the mouth, esophagus, stomach, small intestine, large intestine, and anus. The liver, pancreas, and gallbladder are the solid organs of the digestive system. Why is digestion important? Digestion is important because your body needs nutrients from food and drink to work properly and stay healthy. Proteins, fats, carbohydrates, vitamins, minerals, and water are nutrients. Your digestive system breaks nutrients into parts small enough for your body to absorb and use for energy, growth, and cell repair. Proteins break into amino acids Fats break into fatty acids and glycerol Carbohydrates break into simple sugars ALIMENTARY CANAL Once food is ingested (taken into the body), it undergoes both mechanical and chemical digestion as it is broken down. Mechanical digestion breaks down food into smaller molecules without chemical change. This occurs in the mouth due to chewing and in the stomach as food is churned. Chemical digestion is the breaking down of large, insoluble molecules into smaller, soluble molecules with the use of enzymes, so that the products can be absorbed. Absorption occurs as the smaller molecules and ions pass through the walls of the small intestine into the blood. These molecules then travel around the body, where they are assimilated into the cells and used in metabolic reactions. Food that is not digested and absorbed is egested as faeces. Circulatory System: The circulatory system acts as the main transport system in animals. It is made up of blood vessels such as arteries, veins and capillaries, in which blood travels around the body, carrying nutrients and waste products. Component of the blood: ● Red blood cells - contain haemoglobin (protein) which binds to oxygen, allowing it to be transported around the body to cells. ● White blood cells - play a major role in fighting off infection. A lymphocyte is a type of white blood cell which produces antibodies. Antigens are proteins found on the cell membrane of pathogens. Each antibody is specific to one type of antigen, and they bind to these antigens, causing the foreign cells to clump together. This makes them harmless as they can no longer enter cells to cause damage. White blood cells also carryout phagocytosis. ● Platelets - involved in blood clotting. ● Plasma - the liquid in blood vessels in which contains blood cells, ions, soluble nutrients, hormones and carbon dioxide. Human Respiratory System ● Lungs - The lungs are the main organs in the respiratory system, containing the surfaces where gas exchange takes place. ● Ribs and intercostal muscles - Intercostal muscles are found between the ribs. Internal and external intercostal muscles work antagonistically in pairs to expand and contract the rib cage during breathing. The ribs also protect the lungs and heart from physical damage. ● Larynx - contains the vocal cords. ● Trachea - connects the throat to the bronchi. C-shaped cartilage rings are present to provide structural strength, keeping the trachea open so that air can pass through it. ● Bronchi - hollow tubes composed of cartilage rings that carry air from the trachea to the lungs. The bronchi split into two tubes to enter the left and right lung, before branching further inside the lungs. ● Bronchioles -Smaller tubes which branch off from the bronchi in the lungs, leading to the alveoli. ● Alveoli - Where gas exchange occurs; comprised of tiny air sacs with a capillary network. Oxygen from the air diffuses into the capillaries, whilst waste carbon dioxide diffuses out. Waste gases are then breathed out. Drugs & Antibiotics Drugs A drug is a substance that, when taken into the body, has an effect on the chemical reactions that take place. There are a variety of different drugs which treat different diseases. Antibiotics Antibiotic drugs are used to treat bacterial infections. Some antibiotics kill bacteria by destroying their cell wall, leading to the cell bursting, whilst others inhibit the growth of the bacteria. Viruses cannot be killed by antibiotics as they do not grow and reproduce in the same way as bacteria, and do not have the same structure. Misused drugs Alcohol and heroin: Alcohol and heroin are both depressants, meaning that they lower the rate of nervous impulses by blocking synapses. This means that reactions are slower. They also lower self-control, which can lead to increased crime rate and antisocial behaviour. These drugs also cause the release of neurotransmitters such as dopamine into synapses in the reward pathway which causes a ‘high’. This can be addictive and thus lead to withdrawal symptoms if the person stops taking the drug, such as anxiety, insomnia, headaches and nausea. They can also lead to other medical problems: ● Heroin is usually injected, thus infections such as HIV are common from sharing dirty needles. ● Excessive alcohol consumption leads to liver damage. The liver usually breaks down alcohol and other toxins. Smoking and diseases: Smoking is addictive due to a chemical called nicotine which is inhaled with the cigarette smoke and causes the release of dopamine. This leads to longterm smoking habits, which have been linked to many diseases: Lung cancer - one of the more serious forms of cancer, for which smoking accounts for over 85% of cases. This is because cigarette smoke contains a variety of toxic chemicals, many of them carcinogens. Coronary heart disease - smoking puts a strain on the heart due to the nicotine and carbon monoxide breathed in. Carbon monoxide is dangerous as it displaces the oxygen bound to haemoglobin and binds to it instead. This means that there is less oxygen present in the blood so the heart must work harder to supply it to the tissues. There is also an increased risk of blood clots, and other chemicals can damage arteries. Coronaryheart disease can lead to heart attacks and heart failure. Components of cigarettes: There is a toxic mix of over 7000 chemicals in every cigarette, many of which are poisons andcarcinogens: ● Nicotine - addictive, causes high heart rate and blood pressure, and also triggers therelease of adrenaline. ● Tar - tar, when inhaled, sticks to the cilia of cells in the lungs which usually transport mucus away from the lungs to protect them from infections. Tar prevents them from doing this, which is why smokers are more susceptible to chest infections. In addition, abuild-up of tar can narrow airways. ● Carbon monoxide - Carbon monoxide decreases the amount of oxygen in the blood, thus putting a strain on the heart to supply more.
