Draw a labelled diagram showing the structure of three water molecules and how they interact.
Aquatic and other environments are being affected by a global rise in temperature. Outline the consequences of this on arctic ecosystems.
Cell membranes separate aqueous environments in cells. Explain how the properties of phospholipids help to maintain the structure of cell membranes.
Explain how cells and cell components in the blood defend the body against infectious disease.
Outline reasons for the therapeutic use of stem cells.
Which of the following characteristics found in a structure necessarily indicates that it is alive?
In which stage of mitosis is the cell labelled X ?
Describe briefly the endosymbiotic theory.
Outline how photosynthesis produces glucose.
Discuss the control of blood glucose levels and the consequences if they are not maintained.
Which characteristics are used to identify chromosomes when constructing a karyotype?
I. The length of the chromosome. II. The position of the centromere on the chromosome. III. The pattern of bands on the chromosome. IV. The position of the chromosome on the spindle.
The data below shows the concentrations of three ions in a frog.
Ion | Concentration / mmol dm | |
---|---|---|
Extracellular fluid | Cytoplasm | |
110.0 | 13.0 | |
138.0 | 2.5 | |
3.0 | 90.0 |
What best explains the distribution of ions?
What can the extracellular matrix of cells be made of?
I. Polysaccharide II. Glycoprotein III. Phospholipid
The diagram shows a section through a typical dicotyledonous leaf.
Which correctly identifies the main functions of the structures labelled X, Y and Z?
X | Y | Z | |
---|---|---|---|
A. | support | gas exchange | photosynthesis |
B. | transport products of photosynthesis | photosynthesis | water conservation |
C. | gas exchange | water conservation | light absorption |
D. | transport water | support | gas exchange |
Which of the following is a metabolic activity of some prokaryotic cells but no eukaryotic cells?