Who was/were responsible for establishing that the hereditary material is carried on chromosomes?
In pea plants, the allele for green pods (G) is dominant over that for yellow pods (g). A plant breeder crosses two pea plants and obtains the following offspring:
When Legionnaire’s disease was first encountered in the United States the health authorities immediately set about finding the causative pathogen. They examined the lungs of people who had died from the disease, and they discovered a rod-like bacterium in all of them. This bacterium was not present in the lungs of healthy people. They isolated this bacterium and grew it in pure culture. What other step would they need to take before they could be justified in naming this bacterium as the causative pathogen?
Base analysis of a sample of DNA has determined that 15% of the sample is made up of the base Guanine. Thus the correct estimate of one of the remaining bases would be
The photograph below is of a fossil trilobite, an extinct invertebrate.
In his book ‘Darwin’s Island’, Steve Jones points out that 20% of the men of North West Ireland have identical Y chromosomes. This is evidence that they are all descended from the same male ancestor, and Jones names a fifth century warlord, ‘Niall the Hostage Taker’ as that ancestor. Of all the human chromosomes, only the Y chromosome can be passed on unchanged from generation to generation.
Transport of materials through plants occurs in the xylem and phloem. Which one of the following is an example of active transport?
A rise in blood solute concentration, detected by the hypothalamus, would trigger:
Many useful products are obtained from donated blood. Choose the line which correctly matches the products with their uses.
The pedigree below shows the inheritance of polycystic kidney disease in a family. The affected gene is carried on chromosome no. 16, and the allele which causes the condition is dominant.
Which one of the following defence adaptations relies upon the release of histamine to stimulate blood flow to the area and encourage flow of fluid from the capillaries into the tissues?
Which one of the following is a factor which influenced Darwin in delaying the publication of his theory?
Louis Pasteur performed a famous experiment in which he sterilised the nutrient broth in two swan necked flasks. He then broke the neck off one of them and found that the broth in the broken flask became infected with microbes, but the broth in the other flask remained clear and uninfected.
The diagram below is of a transverse section through a plant stem.
Candidiasis, or thrush, is a fungal infection which can occur in the female reproductive tract and in the intestine. One of the factors which can trigger it is taking large amounts of antibiotics. This is because: