(a) (i) Name the two stages involved in photosynthesis.
(ii) Write an equation to represent the first stage of photosynthesis.
(b) (i) List six modes of nutrition in organisms.
(ii) Name one feature that makes feeding possible in the following organisms: I. Paramecium; II Spirogyra; Ill Rhizopus; IV Tape worm.
(c) Define the term balanced diet.
(d) (i) State three characteristics of enzymes.
(ii) in a tabular form, indicate the source, substrate acted upon and the product of the following enzymes: ptyalin and pepsin.
Explanation
(a)(i) The two stages involved in photosynthesis are: Light reaction stage or photolysis or Hill’s reaction and Dark reaction stage or Carbon assimilation or Calvin reaction.
(ii) Equation to represent Photolysis 4H(_2)O Light 4H(^{+}/) + 4OH(^{-}/) → chloropyll
(b)(i) Modes of nutrition in organisms are:
(1) Holozoic nutrition
(2) Parasitic nutrition
(3) Symbiotic nutrition
(4) Carnivorous /Insectivorous/Piscevorous nutrition
(5) Herbivorous nutrition
(6) Chemosynthetic nutrition
(7) Photosynthetic/Autotrophic /Holophytic nutrition
(8) Ominivorous nutrition
(9) Heterotrophic nutrition
(b)(ii) Features that made feeding possible in:
(1) Paramecium are: Food vacuole/cilia/ oralgroove/gullet/cytostome
(II) Spirogyra are: Chloroplast/chlorophyll
(III) Rhizopus are: Mycelia/Rhizoids / Hyphae
(IV) Tape worm are: Body surface/flat body/body.
(c) A balanced diet; is a diet containing the correct proportion or right amount of all the six food substances or names of the six food substances or essential food subtances required by the organism/man. OR A balanced diet contains 15% protein, 15% fats and oils, Vitamins, 10%Minerals water and 60% carbohydrates.
(d)(i)Characteristics of enzymes are:
Enzymes
(i) speed up chemical reactions or act as catalysts
(ii) are specific in action
(iii) are not used up or changed during reaction
(iv) Actions of enzymes are reversible.
(v) are affected by temperature or denatured at high temperature
(vi) are affected by pH of their surrounding
(vii) Some enzymes act best in the presence of co-enzymes.
(vii) Enzymes can function outside organisms producing them.
(ix) are protein in nature
(x) Enzymes have active sites.
(xi) Small amount of enzymes catalyze large amounts of substrate.
(d)(ii)
| Enzyme | Source | Substrate | Product |
| Ptyalin Pepsin |
Mouth/salivary Gland/ saliva Stomach/Gastric |
Starch/ Cooked starch Proteins gland/ Gastric juice |
Maltose/ Malt Sugar/dextrin/ dextrose Peptones/ Polypeptides/peptides |