Observation

This question was averagely answered and questions 1 (a) (i), (a) (ii) and (b) (i) were well answered. Question (b) (ii) most candidates could not describe the process of transport of water and mineral salts in the leaves of flowering plants.

The expected answers are:

1. (i)Substances that constitute the lymph in humans
   

   - Dissolved mineral salts/ any correctly named example;

   - Nutrients; fatty acids; glycerol; amino acids; vitamins; glucose;

   - White blood cells;

   - Oxygen;

   - Carbon dioxide;

   - Hormones;

   - Wastes/ nitrogenous waste/urea.;

   (ii)Functions of the lymphatic system

   - Removes foreign bodies from the cell;

   - Collects fatty acids from the villi to the blood;

   - Produces white blood cells/lymphocytes;

   - Lymph nodes filter out bacteria from the body fluids;

   - Removes excretory products/urea from the cells;

   - Collects intercellular/interstitial fluid.

2. (i) Substances that require water medium

   - Hormones;

   - Digested food substances/nutrients;

   - Excretory products/urea;

   - Oxygen;

   - Carbon dioxide;

   - Mineral salts;

   - Antibodies;

   - Enzymes.

   (ii)) Transportation of water and mineral salts into the leaves of flowering plants

   - Water and mineral salts are absorbed into root hair cells by osmosis;

   - Then moves into cells of the cortex by osmosis;

   - Then into the endodermis by cell to cell osmosis along a concentration gradient;

   - Across the Casperean strip;

   - Solution now moves through the pericycle into the xylem tissue of the root;

   - It then moves up to a certain level in the xylem of the stem by root pressure;

   - The solution continues to move up the stem by the forces of cohesion;

   - Adhesion and capillary action;

   - Transpiration pull now takes solution to the veins of the leaves;

   - While mineral salts are selectively reabsorbed by active transport;

   - Involving the use of energy.

3. (i) Placentation
   Is the arrangement of ovules; along the inner walls of the ovary of a flowering plant.

   (ii)Types of placentation in flowering plants

   - Marginal;

   - Parietal

   - Apical;

   - Basal.

   Note: spellings must be correct to score.