Biology Questions and Answers

Answer: B

The key gives mental disorder.

Kundalini yoga, which combines postures, breathing, chanting and meditation, has been taught in the United States and studied in trials for conditions such as post-traumatic stress, anxiety and depression. Because PTSD, anxiety and depression are all mental disorders, the general phrase 'mental disorder' covers the whole range and is the one option that is true whichever condition a study looked at.

I could not find a source naming one disorder as the one the question has in mind. A pilot trial found Kundalini yoga helpful as an add-on for PTSD, but its effects were small and it did not single out PTSD as the treatment. The key's reading is the broad one, so this explanation follows it and the three specific options are rejected as narrower than the claim.

Answer: B

The answer is Only B is correct.

Macronutrients are needed in large amounts: carbohydrates, proteins and fats (and water). Vitamins and minerals are needed in small amounts and are micronutrients, so Statement A is wrong.

Folic acid (vitamin B9) is a micronutrient needed for making DNA and red blood cells and for preventing neural tube defects in the developing foetus, so Statement B is correct.

Answer: C

Involuntary actions such as salivation and vomiting are controlled by the medulla in the hind-brain.

The medulla oblongata, at the base of the brain where it joins the spinal cord, contains centres for vital involuntary actions: heartbeat, breathing and blood pressure, and reflexes such as salivation, vomiting, swallowing, coughing and sneezing.

The fore-brain (cerebrum) handles thinking and voluntary actions, the mid-brain relays visual and auditory reflexes, and the cerebellum, also in the hind-brain, maintains posture, balance and the precision of voluntary movements. None of these controls salivation or vomiting.

Answer: D

The longest snakes in the world are reticulated pythons.

The reticulated python of South-East Asia is the longest snake species, with individuals recorded at over 6 metres and exceptional ones near 7 metres or more.

The green anaconda of South America is the heaviest snake, bulkier but generally shorter, which is why it is the common wrong answer. Boas are smaller constrictors, and vipers are venomous snakes that are mostly short and stout.

Answer: A

The plant group described is the algae. Algae are chlorophyll-bearing, simple, thalloid and autotrophic, and they live largely in water, fresh or marine. The forms range from colonial ones such as Volvox to filamentous ones such as Ulothrix, and they reproduce by vegetative, asexual and sexual methods. Bryophytes (mosses and liverworts) are land plants that need moisture but have a more differentiated body. Pteridophytes (ferns) have vascular tissue, and gymnosperms are seed plants with naked seeds, so neither is a simple thalloid water group.

Answer: C

Carbohydrates are the energy giving nutrients, since they are broken down to glucose, which is used in the body to give energy. Proteins are body building nutrients, and vitamins, such as A and K, are protective nutrients needed in small amounts. Fats also give energy, but they are not among the options.

Answer: A

Proteins are called the body building foods because they supply the amino acids that the body needs for growth and for the repair of tissues, muscle and cells. Carbohydrates and fats are energy giving foods, so they do not build the body in this sense, and an option that combines carbohydrates and fats is also an energy group. Sources of protein are pulses, milk, eggs and meat. The answer is protein, option A.

Carbohydrates and proteins give about 4 kcal per gram and fats about 9 kcal, but only proteins are used mainly to build enzymes, hormones and tissue.

Answer: C

Microsome is not a cell organelle. Microsomes are small vesicles that form from fragments of the endoplasmic reticulum when cells are broken up in the laboratory, so they are artefacts of preparation and do not exist as organelles in the living cell. Ribosomes make proteins, lysosomes digest waste, and mitochondria produce energy as ATP, and all three are true cell organelles. So the microsome is the one that is not an organelle.

Answer: A

Mangrove trees can survive in saline water. They grow along the coasts in the tidal areas, where river water mixes with the sea, and have adaptations such as breathing roots and salt-excreting leaves.

Thorny bushes belong to dry regions, tropical deciduous forests to the monsoon areas with moderate rain, and tropical rainforests to hot regions with heavy rain. None of those grows in salt water.

Answer: B

Camillo Golgi invented the staining technique called the black reaction, in 1873, using a weak solution of silver nitrate that stains a few nerve cells fully, showing their processes and fine details. He shared the Nobel Prize of 1906 with Ramon y Cajal for work on the structure of the nervous system.

Singer and Nicolson proposed the fluid mosaic model of the cell membrane, Albert von Kolliker was an anatomist who studied the nervous tissue, and Waldeyer gave the name neuron. None of them invented this stain.