Which of the following plays an important part in photosynthesis?
Answer: A
The chloroplast carries out photosynthesis.
Its thylakoid membranes hold the chlorophyll that captures light, and the surrounding stroma holds the enzymes that fix carbon dioxide into sugar. A leaf cell may contain fifty or more.
Please log in or register to report this question.
Which vitamin is required for the clotting of blood ?
Answer: D
Correct answer: Vitamin K
Vitamin K is needed to synthesise prothrombin and several other clotting factors in the liver. A deficiency prolongs bleeding, which is why newborn infants are routinely given a dose at birth.
Please log in or register to report this question.
Movement of cell against concentration gradient is called
Answer: B
Movement against a concentration gradient is active transport.
It moves a substance from low concentration to high, so it needs energy, supplied by ATP through carrier proteins. The sodium-potassium pump in every animal cell is the standard example. Osmosis and diffusion both run down the gradient and need no energy.
Please log in or register to report this question.
Biological control is to check growth of
Answer: D
Biological control means checking one pest by another organism.
A natural enemy - a predator, parasite or pathogen - is introduced against the pest. The ladybird beetle against aphids and Bacillus thuringiensis against caterpillars are examples; it avoids the residues and resistance that chemicals bring.
Please log in or register to report this question.
Radical vascular bundles are those in which
Answer: D
In a radial vascular bundle the xylem and phloem lie on different radii, alternating around the axis.
This is the arrangement in roots. In stems the two lie on the same radius, phloem outside xylem, forming collateral bundles.
Please log in or register to report this question.
In which of the following organelles does photosynthesis take place?
Answer: B
Photosynthesis takes place in the chloroplast.
Its thylakoid membranes hold the chlorophyll that captures light, and the stroma around them holds the enzymes of the Calvin cycle that fix carbon dioxide into sugar. A leaf cell may contain fifty or more.
Please log in or register to report this question.
Which of the following hormones is called the emergency hormone?
Answer: B
Adrenaline is called the emergency hormone.
Released from the adrenal medulla under stress, it speeds the heart, raises blood pressure and blood sugar, widens the airways and diverts blood to the muscles - the fight-or-flight response that prepares the body for sudden effort.
Please log in or register to report this question.
Out of 900 reported species of living gymnosperms, conifers are represented by about 500 species, About 2,50,000 species of angiosperms (flowering plants) have also been reported in the world. The vas
Answer: C
Only the conifers match the description.
They are about 500 of the 900 living gymnosperm species, over half the group, while the 250,000 angiosperms make the conifers a small fraction of seed plants as a whole - yet they dominate the northern forests.
Please log in or register to report this question.
A flower bud which is used as a spice is obtained from
Answer: C
Clove is a dried flower bud, of Syzygium aromaticum, picked before it opens.
Its aroma comes from eugenol, which makes up most of clove oil and is used as a local anaesthetic in dentistry. Cinnamon is bark, cardamom a fruit and coriander a seed.
Please log in or register to report this question.
Pyorrhoea is a disease of the
Answer: B
Pyorrhoea is a disease of the gums - periodontitis, in which the gum recedes from the teeth and the pockets discharge pus.
It follows untreated gingivitis, destroys the bone supporting the teeth, and is the commonest cause of tooth loss in adults.
Please log in or register to report this question.
