Biology

BIOLOGY AS AN INQUIRY IN SCIENCE Science is the study of nature (living and non-living things).  Biology is a science that studies living things in nature. Biology was formed from the Greek words “Bio” (meaning life) and “logos” (meaning, study of). The organisms studied in biology are generally classified into plants and animals. Therefore, biology […]

This is a yellow colouration of the skin and eyes. Cause: Presence of excess bile pigments. This happens due to blockage of bile duct or destruction of liver. Symptoms: Yellow pigmentation of skin and eyes, nausea, vomiting and lack of appetite. Itching of skin. Treatment Removal of stones from the gall bladder by surgery. Give

Role of Liver in Excretion The liver lies below the diaphragm and it receives blood from hepatic artery and hepatic portal vein. Blood flows out of the liver through hepatic vein. Excretion of Nitrogenous Wastes Excess amino acids cannot be stored in the body; they are deaminated in the liver. Hydrogen is added to amino

The kidneys are organs whose functions are excretion, osmoregulation and regulation of pH. Kidneys are located at the back of the abdominal cavity. Each kidney receives oxygenated blood from renal artery, while deoxygenated blood leaves through the renal vein. Urine is carried by the ureter from the kidney to the bladder, which temporarily stores it.

What is Excretion? Excretion is the process by which living organisms separate and eliminate waste products of metabolism from body cells. If these substances were left to accumulate, they would be toxic to the cells. Egestion is the removal of undigested materials from the alimentary canals of animals. Secretion is the production and release of

Asthma Asthma is a chronic disease characterized by narrowing of air passages. Causes: Allergy Due to pollen, dust, fur, animal hair, spores among others. If these substances are inhaled, they trigger release of chemical substances and they may cause swelling of the bronchioles and bring about an asthma attack. Heredity Asthma is usually associated with

Factors that cause a decrease or increase in energy demand directly affect rate of breathing. Exercise, any muscular activity like digging. Sickness Emotions like anger, flight Effects of Exercise on Rate of Breathing Students to work in pairs. One student stands still while the other counts (his/her) the number of breaths per minute. The student

The breathing system of a mammal consists of a pair of lungs which are thin-walled elastic sacs lying in the thoracic cavity. The thoracic cavity consists of vertebrae, sternum, ribs and intercostal muscles. The thoracic cavity is separated from the abdominal cavity by the diaphragm. The lungs lie within the thoracic cavity. They are enclosed

An adult frog lives on land but goes back into the water during the breeding season. A frog uses three different respiratory surfaces. These are the skin, buccal cavity and lungs. Skin The skin is used both in water and on land. It is quite efficient and accounts for 60% of the oxygen taken in

Gaseous exchange in fish takes place between the gills and the surrounding water. The gills are located in an opercular cavity covered by a flap of skin called the operculum. Each gill consists of a number of thin leaf-like lamellae projecting from a skeletal base branchial arch (gill bar) situated in the wall of the

Gaseous exchange in insects e.g., grasshopper takes place across a system of tubes penetrating into the body known as the tracheal system. The main trachea communicate with atmosphere through tiny pores called spiracles. Spiracles are located at the sides of body segments; Two pairs on the thoracic segments and eight pairs on the sides of

All animals take in oxygen for oxidation of organic compounds to provide energy for cellular activities. The carbon (IV) oxide produced as a by-product is harmful to cells and has to be constantly removed from the body. Most animals have structures that are adapted for taking in oxygen and for removal of carbon (IV) oxide

Gaseous exchange takes place by diffusion. The structure of the leaf is adapted for gaseous exchange by having intercellular spaces that are filled. These are many and large in the spongy mesophyll. When stomata are open, carbon(IV)oxide from the atmosphere diffuses into the substomatal air chambers. From here, it moves into the intercellular space in

The water lily, Salvia and Wolfia whose stems remain in water are permeable to air and water. Oxygen dissolved in the water diffuses through the stem into the cells and carbon (IV) oxide diffuses out into the water. Gaseous Exchange in Roots Terrestrial Plants Gaseous exchange occurs in the root hair of young terrestrial plants.

Living organisms require energy to perform cellular activities. The energy comes from breakdown of food in respiration. Carbon (IV) oxide is a by-product of respiration and its accumulation in cells is harmful which has to be removed. Most organisms use oxygen for respiration which is obtained from the environment. Photosynthetic cells of green plants use

Oxygen is required by plants for the production of energy for cellular activities. Carbon (IV) oxide is required as a raw material for the synthesis of complex organic substances. Oxygen and carbon (IV) oxide are obtained from the atmosphere in the case of terrestrial plants and from the surrounding water in the case of aquatic

Making of beer and wines. Ethanol in beer comes from fermentation of sugar (maltose) in germinating barley seeds. Sugar in fruits is broken down anaerobically to produce ethanol in wines. In the dairy industry, bacterial fermentation occurs in the production of several dairy products such as cheese, butter and yoghurt. In production of organic acids

Carbohydrate, mainly glucose is the main substrate inside cells. Lipids i.e. fatty acids and glycerol are also used. Fatty acids are used when the carbohydrates are exhausted. A molecule of lipid yields much more energy than a molecule of glucose. Proteins are not normally used for respiration. However during starvation they are hydrolysed to amino

COMPARISON BETWEEN ENERGY OUTPUT IN AEROBIC AND ANAEROBIC RESPIRATION Aerobic respiration results in the formation of simple inorganic molecules, water and carbon (Iv) oxide as the by¬products. These cannot be broken down further. A lot of energy is produced. When a molecule of glucose is broken down in the presence of oxygen, 2880 KJ of

BIOLOGY PRACTICAL ACTIVITIES To Show the Gas Produced When the Food is burned A little food substance e.g., maize flour or meat is placed inside a boiling tube. The boiling tube is stoppered using a rubber bung connected to a delivery tube inserted into a test-tube with limewater. The food is heated strongly to bum.