An explanation of the results of Gregor Mendel’s research into the heredity of the common pea plant. How he cross bred pure bred plants with purple and white flowers; the results of this cross breeding programme in the first generation; how the self pollination of the first generation led to the offspring in the second generation developing purple and white flowers in the ratio of 3:1; an explanation of hybrids.
An introduction to the work of the father of genetics, the 19th century monk Gregor Mendel; how he set up experiments to investigate the heredity of the common pea plant; an explanation of the seven traits he decided to investigate; the meaning of ‘trait’ and revision of phenotypes and genotypes; opposition to his conclusions; a summary of the 19th century hypothesis of ‘blending inheritance’.
A brief explanation of the principles of Mendelian genetic inheritance; patterns of genetic inheritance introduced using Punnett squares; an explanation of genetic inheritance of brown/blue eye colours; an introduction to alleles and gene variations; ‘phenotypes’ and ‘genotypes’; dominant and recessive alleles; probability of being born with brown eyes if parents have the genotypes ‘BB and bb’.
The difference between inheritance and evolution; how inheritance describes traits that you inherit from your parents; how evolution describes inherited traits over time and through successive generations; some common traits that you could inherit from your parents such as blue eyes, ‘hitchhikers’ thumbs or a ‘dimpled’ chin; some inherited traits described by society as being ‘disabling’.
This article gives an example of evolution by natural selection which takes place over a very short period of time. The article summarises the work undertaken by the evolutionary biologist Dr Endler, whose experiment under laboratory conditions saw guppy fish change the colour of their skins in just over a year. His laboratory work replicated his observations in the field in the mountain streams of Trinidad and Tobago.
Early theories about the motion of falling objects; characteristics of objects in freefall; how the shape,cross sectional area and mass of different objects affect the speed of objects in freefall; the hammer and feather experiment as carried out on the Moon in 1971; two different types of freefall; reaching terminal velocity; how aerodynamic drag and and the force of gravity affects skydivers.
This article investigates the three main forces of drag- namely aerodynamic drag, hydrodynamic drag and frictional drag. We consider the following: reasons why objects in forward motion slow down; effects of aerodynamic drag on cyclists and formula 1 racing cars; evolution of underwater predators with streamlined shapes; how dolphins have evolved to reduce skin drag by shedding their skin as they swim through water.
How astronauts’ mass remains constant no matter what planet they visit in our solar system; how weight would change on different planets as a result of differing forces of gravitational attraction. How measuring your weight actually measures the force of gravitational attraction between you and the planet you are visiting. A ‘true’ story about how Homer Simpson would like to lose weight by visiting other planets!
This science teaching resource considers the issue of ‘weightlessness’ and addresses the common misconception that ‘weightlessness’ means there can be little or no gravity in space.The reasons why astronauts appear to ‘float’ in space are explained; rockets need to reach high velocities in orbit and the spherical shape of the Earth means that the surface of the Earth is forever disappearing.
An introduction to the force of gravity. The meaning of ‘mass’ and how we need to understand ‘mass’ before can understand ‘gravity’. Gravity is discussed with reference to Planet Earth, the Moon and the Solar System. We look at examples of gravitational forces and how the forces of gravity affect our everyday lives. The gravitational force the Sun exerts on the planets in our Solar System.