Biology For Igcse Students Essay Research Paper

Starch changes to Maltose which change to Glucose by the action of Amylase

Protein changes to Peptides which change to Amino acids by the action of Protease

Fats change to Glycogen and Fatty acids by the action of Lipase

The only groups absorbed without any digestion are water, vitamins and sugars

Saliva in mouth consists of the enzyme Amylase which consists of Ptyalin

Pepsin is made in stomach, it acts on proteins and changes them to Peptides

Bile (pancreatic juice) neutralizes food in the duodenum

Minerals and vitamins are stored in liver

Plasmolysis is the effect of a cell loosing water when it is surrounded by a more concentrated solution than its cell sap

The final products of digestion are Fatty acids, Glucose, Glycerol, Amino acids

Plants need nitrogen for protein for cell repair and growth

Plants need Potassium for enzyme activity

Plants need Magnesium for chlorophyll to carry out photosynthesis

Plants need calcium to maintain their cell wall which gives them a rigid shape

One molecule of fat is made up of three molecules of fatty acids and one molecule of glycerol

Scurvy is caused by vitamin C (used to keep body tissue healthy) and D deficiency

Ricketts is caused by vitamin D (used to absorb calcium) deficiency

Anemia is caused by Iron deficiency

Fibrinogen is a protein in blood that changes to Fibrin to block damaged vessels and form blood clot to reduce bleeding. It is formed in the liver

The main difference between Vascular plants and Bryophytes is that vascular plants have well developed conducting tissue

Rennin is an enzyme produced in the stomach of mammals

Monosaccharide – glucose

Disaccharide – maltose

Polysaccharide – glycogen, starch

Xylem transport water and mineral salts from the soil, through the roots, up the stem and into the leaves for photosynthesis

Lactic acid bacteria in milk change milk sugars to acid, this is responsible for the formation of milk products such as yogurt, cheese etc.

During respiration, glucose is oxidized to carbon dioxide and water

Transpiration is important because it results in photosynthesis, it keeps walls of spongy mesophyll moist which is good for the absorption of carbon dioxide and evaporation of water has a cooling effect which reduces chances of cells being damaged by intense heat

In a human heart, oxygenated blood enters the Left Atrium through Pulmonary vein; from here, it goes to the Left Ventricle, which pushes it out through the Aorta to be taken to all body parts. The deoxygenated blood enters the Right Atrium through the Vena Cava; from here, it goes to the Right Ventricle, which pushes it out through the Pulmonary artery to be taken to the lungs

Systole is the contraction of heart muscle and Diastole is the relaxing of heart muscle.

Pulmonary circulation conveys blood to and from the lungs

Systemic circulation conveys blood to and from all parts of the body

Oxygen concentration in inspired air is 20% and 16% – 20% in expired air

Carbon dioxide concentration in inspired air is 0.04% and 4% in expired air

Nitrogen concentration in inspired air is 74% and 74% in expired air

Osmoregulation is the control of movement of water in and out of cells by osmosis to avoid dehydration

Sense organs are the receptors of the body, which receive stimulus, which result in a wave of impulses to the brain. Light, mechanical, chemical, stretch and temperature receptors are the main kinds of receptors

Cones enable us to distinguish color, they are concentrated in Fovea

Rods do not distinguish color, they are present in retina

Stimulus is any change, in or outside the body which provokes a change in behavior

Receptors are sense organs which detect stimulus

Coordinators are the brain and the spinal chord; which receive information from the receptors

Effectors are parts of body controlled by coordinators e.g. Muscles

Motor neurons carry impulses from central nervous system to muscles and glands

Sensory neurons carry impulses from receptors to central nervous system

Multi-polar neurons make connections with other neurons beside those of CNS

Medulla Oblongata is concerned with temperature control, blood pressure regulation, heart beating and breathing. Cerebellum maintains a balanced posture, controls muscles while walking, running etc. Cerebrum is concerned with all types of conscious activities, sensations such as touch; smell, vision and hearing are activated here. Decisions are made, memories are stored, and emotions are felt with the help of Cerebrum

Placenta has villi, which are made of embryonic tissue. These villi consist of maternal and embryonic capillaries allowing exchange of materials between mother and embryo

Umbilical chord consists of two umbilical arteries, which carry waste from embryo to mother and one umbilical vein which carries nutrients from mother to embryo

Gonorrhea s symptoms include pus discharge from urethra and pain, the urethra can be blocked making the infected person sterile

Syphilis is more common between homosexual men who practice anal intercourse. First few years go by without symptoms, later a lump appears on penis or vulva, bacteria enter body and effect tissue, heart and brain causing insanity or paralysis

HIV weakens the body s immune system and so making it vulnerable to all kinds of diseases. Death is not the result of HIV but of diseases caused by it. HIV is transmitted by blood transfusion and sexual intercourse. Its more common between homosexual men who practice anal intercourse.

Nitrifying bacteria change nitrites to nitrates

Putrefying bacteria change urea to ammonia

Nitrogen fixing bacteria change nitrogen gas to nitrates

Denitrifying bacteria change nitrates back to nitrogen gas. They live in roots of leguminous plants

Sycamore and poppy are wind dispersed, apples and strawberries are animal dispersed.

Plumule is the small shoot, radical is the small root and cotyledon is the food store.

Litmus turns red in acid and blue in alkali.

Pondweed photosynthesizes rapidly in carbonated water than pure water.

At 30 degrees, water in seeds evaporated but the seeds don t die.

Oxygen is very important for decaying because it the bacteria respired anaerobically, they would produce lactic acid which prevents decay.

Oestrogen and Progesterone prepare uterus lining for implantation after ovulation by making it thick and providing blood vessels. If no fertilization occurs, hormone production stops leading to breaking up of uterus lining leading to menstruation.

Active transport needs energy from respiration.

In most dicotyledons, stomata are present on the lower surface only.

In monocotyledons, stomata are distributed equally on both the sides.

AEROBIC respiration = C H O + 6O _____ 6CO + 6H O + 2898 kj

ANAEROBIC respiration = C H O _____ lactic acid + 150 kj

Liver regulates blood sugar level, produces bile which is stored in gall bladder and poured in duodenum to emulsify fat, deaminates (removal of amino part), detoxicates ( removal of poisonous products of metabolism), stores iron, manufactures proteins.