Biology 4BI1/2B May Jun 2021

Edexcel IGCSE Biology (4BI1) Jun 2021

معلم موافق رایگان بودن است.

1. Male Contraception and Hormones: Role of progestin and testosterone in suppressing sperm production, effectiveness of hormonal injections, side effects like acne and mood disorders, and sperm count recovery post-treatment.

2. Bacterial Structure and Immunity: Comparison of bacterial and eukaryotic cells, immune response to weakened bacteria, role of antibodies in long-term immunity, and bacterial classification as pathogens.

3. Plant Biology and Transpiration: Water absorption by root hair cells, differences between osmosis and diffusion, effect of light on water uptake, and controlled variables in transpiration experiments.

4. Fish Growth and Environmental Impact: Effect of water quality on fish growth, bacterial presence in unfiltered water, calculation of mean growth rate, and methods to control interspecific predation.

5. Nitrogen Cycle and Enzymes: Urease activity in decomposer bacteria, optimum pH for enzyme function, nitrogen-fixing bacteria roles, and processes of nitrification and denitrification in soil.

6. Kidney Function and Diabetes Insipidus: Ultrafiltration and glucose reabsorption in the nephron, ADH deficiency effects on blood concentration, treatment using desmopressin, and changes in urine production.