Biology B1.1


Diet and Exercise

Carbs, fats and proteins are used by the body to release energy and to build cells. A person loses weight when the energy content of the food take in is less than the amount of energy expended by the body. The rate at which all the chemical reactions in the cells of the body are carried out is the metabolic rate.

Bacteria and viruses may reproduce rapidly inside our body. Viruses damage the cells in which they reproduce. The body protects itself by 

Ingesting pathogens

Producing antibodies, which destroy particular bacteria or viruses.

Producing antitoxins, which deter the toxins released by the pathogens. 

Semmelweis recognized the importance of hand washing in the prevention of diseases. By getting doctors to wash their hands before and after dealing with patients he saved many lives. 

Painkillers help to relieve the symptoms but do not kill the pathogens. Antibiotics such as penicillin kill bacteria within the body. However they cannot deal with viruses as they are inside the cells, which we need. We must be careful in our use of antibiotics of resistant strains such as MRSA develop due to natural selection. 

A vaccination is basically injecting the body with a weakened or dead part of a virus so that the body can produce antibodies and antitoxins to deal with it in the future. 

In schools and laboratories in colleges incubation must be done at 25 to stop harmful bacteria emerging. The higher temp however the higher the rate of growth. 

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Biology B1.2 Nerves and Hormones

Simple reflex arc(

Reflex actions are automatic and rapid. Synapses between the neurones have receptor sites to detect the chemical released so that they can transmit the signal furhter along the arc to the effector.

In the human body we control the water content, ion content, the blood sugar levels and the temperature.

In the menstrual cycel

  • follicle stimulating hormone (FSH) is secreted by the pituitary gland and causes eggs to mature in the ovaries. It also stimulates the ovaries to produce hormones including oestrogen

  • luteinising hormone (LH) stimulates the release of eggs from the ovary

  • oestrogen is secreted by the ovaries and inhibits the further production of FSH

  • The first birth-control pills contained large amounts of oestrogen. These resulted in women suffering significant side effects 

IVF involves giving a mother FSH and LH to stimulate the maturation of several eggs.
The eggs are collected from the mother and fertilised by sperm from the father. The fertilised eggs develop into embryos. At the stage when they are tiny balls of cells, one or two embryos are inserted into the mother’s uterus (womb). 

Auxin controls phototropism and gravitropism (geotropism). The responses of plant roots and shoots to light, gravity and moisture are the result of unequal distribution of hormones, causing unequal growth rates. 

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Biology B1.3 The Use and Abuse of Drugs

Statins lower the risk of heart and circualotry diseases Thalidomide is a drug that reduces the effects of morning sickness in preganant women but led to abnormalities of their children Drugs change chemical processes in the body so they become dependent and have withdrawal symptoms. 

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Biology B1.4 Interdependence and adaption

Some organsims live in envitoment that are extreme and are called extromphiles. 

Animals adapt to hteir envroments by controlling their

Surface area

thickness of insulating coat

body fat


Plants however change their

Surface area 

Water stroage tisue 

Roots systems

However changes in the enviroment affect the placement of living organisms.

  1. Living organisms can be used as indicators of pollution:

    • lichens can be used as air pollution indicators, particularly of the concentration of sulfur dioxide in the atmosphere

    • invertebrate animals can be used as water pollution indicators and are used as indicators
      of the concentration of dissolved oxygen in water. 

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Biology B1.5 Energy and Biomass in foods

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