Theory question 102
Animal Nutrition(a) Describe the general arrangement of the viscera of a named mammal
(b) Describe the process of feeding in: (i) Hydra (ii) Amoeba
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(a) Named mammal e.g. rabbit; body cavity divided by the diaphragm into thorax and abdomen
Thorax (protected by ribs): heart in the pericardium between two lungs in pleural cavities; trachea and oesophagus run through it
Abdomen: liver just below the diaphragm; stomach on the left; small intestine coiled in the middle, then caecum and appendix, colon and rectum to the anus; pancreas in the loop of the duodenum; spleen near the stomach; two kidneys against the back wall with ureters to the bladder; reproductive organs in the lower abdomen; all held by mesenteries
(b)(i) Hydra: tentacles catch small animals (e.g. water fleas) using stinging cells (nematocysts) that paralyse them; tentacles push the prey into the mouth; enzymes from endoderm cells digest it in the enteron (extracellular), then cells take in particles and finish digestion in food vacuoles (intracellular); undigested matter goes out through the mouth
(ii) Amoeba: puts out pseudopodia around the food (e.g. a diatom) – phagocytosis; food enclosed in a food vacuole with a little water; enzymes secreted into the vacuole digest it; digested food diffuses into the cytoplasm; undigested remains are left behind (egested) as the Amoeba moves on
Name the mammal before describing its viscera.