10 Science Solved Sample Paper 3 – Page 4
Question: 18. (1). Define excretion. Name any two substances that are selectively reabsorbed.
(2). Draw and label the following parts in the human excretory system. 
(i). Right kidney (ii). Urinary Bladder (iii). Right renal artery
(1). Draw a sectional view of the human heart and label on it, Pulmonary artery; Right auricle; Vena cava; Pulmonary vein
(2). Explain why ventricles have thick muscular walls than the atria?
Answer: (2). Ventricles have thicker muscular walls than atria, as the ventricles have to pump the blood to Arteries which carry it to the longer distances.
Question: 19. A person cannot see distinctly the book placed nearer than 60 cm from his eyes.
(1). Name the defect of vision the person is suffering from.
(2). List two possible causes of this detect.
(3). Draw a ray diagram to show this vision defect.
(4). How can this defect be corrected?
(5). Draw a ray diagram to show the correction of this defect. 
Hint: (1). Hypermetropia; (2). (i). Low converging power of eye-lens, (ii). Eye ball becomes short (3). Hypermetropia is corrected by using spectacles containing convex lens.
Question: 20. (1). Name any three functional groups present in carbon compound and write their formulae.
(2). Draw the structure of the following compounds indicating the functional group present in each: propanal, propanone, propanoic, propanol. 
(i). Alcoholic group ⇒ —OH;
(ii). Aldehyde ⇒ —CHO;
(iii). Ketone ⇒ >C = O
Propanoic acid: CH3 — CH2 — COOH; Propanol: CH3— CH2 — CH2OH
Draw the structural formulae of all the possible of the compound with the molecular formula C3H6O and also give their electron dot structures.
(1) Name the part of a bisexual flower that produces male and female germ cells.
(2). Draw a longitudinal section of the female reproductive part of a flower showing germination of pollen grain.
Label – (i) stigma, (ii). pollen tube with germ cells, (iii). female germ cells, (iv). Style.
(3). Name the part of flower that develops into a (i). seed and (ii) fruit. 
Hint: (1). Anther = male germ cells; Ovary = female germ cells; (3). Ovule ⇒ seeds; Ovary ⇒ fruit
When a moist slice of bread was kept in and dark place for a couple of days, some organisms grew on it to form a fluffy cottony mass which later turned black. On seeing through a magnifying glass some thread like projections and thin filaments having bulb like structures at the tip were observed. 
(1). Write the common name of the organism observed. Name the mode of reproduction that made the organism grow and spread and label its parts.
(2). Draw the diagram of the organism observed and label its parts.
(3). Name and write about the structure of the cells that are responsible for its reproduction.
Hint: (1). Bread mould → Spore formation; (3). ‘Spores’