Serial Dilution – Practical Skills Ep 3

Producing a serial dilution is a really useful skill for all sort of biology experiments. In this article we will look at how to prepare a serial dilution, and how it could be used to produce a calibration curve for a colorimeter experiment. How to prepare a serial dilution In A-Level biology, you will probably... Continue Reading →

Cystic Fibrosis – Diseases Ep 3

Cystic fibrosis is an inherited disorder affecting specific channel proteins in cell membranes. In this article we will look at how it is inherited, how chloride ion transport is affected, and the symptoms which develop as a consequence. Inheritance of cystic fibrosis Cystic fibrosis is an inherited recessive disorder, meaning it is caused by a... Continue Reading →

Biochemical Tests – Practical Skills Ep 2

In A-Level biology, there are four biochemical tests to learn for four different biological molecules. This article gives full details of the tests, and a helpful colour summary at the bottom. Test for reducing and non-reducing sugars A sugar is a monosaccharide or disaccharide. The vast majority of sugars learnt about in A-Level biology (glucose,... Continue Reading →

HIV and AIDS – Diseases Ep 2

HIV (human immunodeficiency virus) is a virus which can eventually lead to development of AIDS (acquired immunodeficiency syndrome). However, it is not the virus itself which causes AIDS symptoms; HIV weakens the immune system, meaning other infections can take hold more easily. In this article we will look at HIV structure, replication, and development of... Continue Reading →

Cardiovascular Disease – Diseases Ep 1

Cardiovascular disease is a non-communicable disease; it is not caused by a pathogen and cannot be passed from person to person. Most cardiovascular disease begins with atherosclerosis developing in an artery due to factors such as high blood pressure. In this article we will look at how atheromas develop, cardiovascular disease risk factors, and treatments.... Continue Reading →

Epistasis – Inheritance Ep 5

Epistasis is when the expression of an allele of one gene masks the expression of the alleles of another. The genes must code for the same characteristic in order for this to work. Let's use flower colour as an example. Epistasis example: flower colour In the diagram below, the flower pigment molecule begins as white.... Continue Reading →

Dihybrid Inheritance – Inheritance Ep 3

Dihybrid inheritance looks at the possibilities of two characteristics being inherited together. Each characteristic is coded for by a separate gene. In this case it is much easier to use a Punnett square to work out the possible genotypes of the offspring as a genetic diagram would get very messy and difficult to read. In... Continue Reading →

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