47 questions. Try each one, then open the answer to check yourself and read the explanation.
Question 1
Structure of Flowering Plants
Root hairs are developed from the
A.root apex
B.epidermis of roots
C.vascular bundles
D.endodermis
E.pericycle
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Answer: B (epidermis of roots)
Explanation
Each root hair is a long, thin outgrowth of a single epidermal cell of the root (the piliferous layer). The pericycle gives rise to lateral roots, not root hairs.
Use Fig. 1 to answer questions 2-4. Fig 1 represents a cross section of part of a dicot plant. Which of the following features can be used to identify Fig. 1?
A.Position of 7
B.Its circular nature
C.Number of 5
D.Presence of 3
E.Width of 2
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Answer: A (Position of 7)
Explanation
Fig. 1 is a young dicot root: the xylem (7) forms a star in the very centre with the phloem between its arms. This central, radial position of the xylem is what marks it out as a root.
Use Fig. 1 to answer questions 2-4. Fig 1 represents a cross section of part of a dicot plant. The main function of 4 is to
A.surround the inner tissues
B.produce cork
C.produce root hairs
D.produce lateral roots
E.produce more of 3
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Answer: D (produce lateral roots)
Explanation
In a root, the pericycle is the layer just inside the endodermis. Its cells can divide to form lateral (branch) roots, which push out through the cortex.
In woody plants, gases and water vapour are transported across the stems by the
A.xylem fibres
B.medullary rays
C.sieve tubes
D.phloem fibres
E.phloem parenchyma.
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Answer: B (medullary rays)
Explanation
Medullary rays are bands of parenchyma running outwards from the centre of the stem to the bark. They carry water, food and gases sideways across the stem.
Which of the following substances is NOT found in urine?
A.Water
B.Sodium chloride
C.Nitrogenous compounds
D.Calcium chloride
E.Nitrogenous salts
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Answer: D (Calcium chloride)
Explanation
Urine is mainly water with urea and other nitrogenous compounds and salts such as sodium chloride. Calcium chloride is not one of its normal components.
The kidneys of all vertebrates act as osmoregulators. This means that they
A.keep the composition of the plasma constant
B.regulate osmotic processes
C.control the volume of blood entering the kidneys
D.decrease the osmotic pressure of blood.
E.increase the osmotic pressure of blood.
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Answer: A (keep the composition of the plasma constant)
Explanation
Osmoregulation means keeping the water and salt content (and so the osmotic pressure) of the blood plasma constant. The kidneys do this by removing more or less water and salts.
The movement of part of a plant in response to external stimulus of no particular direction is
A.taxism
B.tropism
C.haptotropic movement
D.nastic movement
E.phototropism.
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Answer: D (nastic movement)
Explanation
Nastic movements, such as the closing of flowers at night, respond to a stimulus but not to its direction. Tropisms depend on the direction of the stimulus.
28 g soil sample was heated to a constant weight of 24g. When further heated to red hot and cooled, it weighed 18 g. What is the percentage of humus in the soil?
A.22.2
B.55.6
C.75.0
D.25.0
E.35.7
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Answer: D (25.0)
Explanation
Heating to constant weight drives off water, leaving 24 g of dry soil. Red heat burns off the humus: 24 − 18 = 6 g. Percentage humus in the dry soil = 6/24 × 100 = 25.0%.
A centipede has a pair of poison claws behind the head for killing prey. A millipede has no poison claws, and it has a cylindrical body with two pairs of legs on most segments.
In what order do the following structures develop during the metamorphosis of the toad? 1 External gills 2. Internal gills 3. Forelimbs 4. Hindlimbs 5. Mouth
A.1 2 3 4 5
B.1 5 2 4 3
C.2 1 3 4 5
D.5 3 4 1 2
E.5 4 3 2 1.
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Answer: B (1 5 2 4 3)
Explanation
The tadpole first has external gills, then its mouth opens, then internal gills form. The hindlimbs appear before the forelimbs.
Which of the following statements is NOT true of insectivorous plants?
A.They obtain part of their food by trapping and feeding on insects
B.They attract insects simply because of pollination
C.They can grow in soils poor in nitrogenous salts.
D.They can supplement their nitrogen supply by feeding on insects
E.Examples include butterworts, sundews and pitcher plants.
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Answer: B (They attract insects simply because of pollination)
Explanation
Insectivorous plants trap and digest insects to get extra nitrogen, which lets them grow in nitrogen-poor soils. They attract insects to catch them, not just for pollination.
Starting from the skull end, the vertebrae are arranged in the following order
A.axis, atlas, cervical, thoracic and lumbar
B.atlas, cervical, axis, thoracic and lumbar
C.atlas, axis, thoracic, cervical and lumbar
D.atlas, axis, cervical thoracic and lumbar
E.atlas, thoracic, cervical, axis and lumbar.
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Answer: D (atlas, axis, cervical thoracic and lumbar)
Explanation
The atlas is the first vertebra (it holds the skull), then the axis, then the other cervical (neck) vertebrae, then the thoracic and then the lumbar vertebrae.
Which of the following statements on the mammalian circulatory system is NOT true?
A.Blood in the pulmonary artery is richer in oxygen content than blood in the pulmonary vein
B.The blood in the hepatic portal vein is the richest in food substances
C.Blood flow is controlled by valves in the veins
D.Arteries are generally thicker and larger than veins
E.Fibrin helps in the formation of blood clot.
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Answer: A (Blood in the pulmonary artery is richer in oxygen content than blood in the pulmonary vein)
Explanation
The pulmonary artery carries deoxygenated blood to the lungs, and the pulmonary vein brings oxygenated blood back, so statement A is the wrong way round.
Glucose absorbed in the ileum goes in the hepatic portal vein to the liver, leaves the liver in the hepatic vein, and reaches the heart through the vena cava.