Biology GK Questions Quiz-20

Biology GK Questions Quiz-20

Biology Multiple Choice Questions (MCQs) Quiz for State and UPSC Civil Services Examinations. Objective Questions on Biology for competitive examinations.

    381. In a food chain, the solar energy utilized by plants is only

    (1) 10 per cent
    (2) 1 per cent
    (3) 0.1 per cent
    (4) 0.01 per cent
    381. (3) Plants, on average, capture only about 0.1 percent of the solar energy reaching Earth. However, it does not mean that the other 99.9 percent is a “vast untapped reservoir” awaiting man’s exploitation. All biological systems, including crops, follow the second law of thermodynamics when solar energy (a highenergy form) is converted into chemical energy. Plants utilize this chemical energy in the process of building their own tissue. Some of the energy being changed from light to chemical energy is lost as heat that dissipates into the surrounding environment. In agricultural ecosystems, an estimated 15 million kcal of solar energy (net production) is fixed per ha per crop season. Even so, this amounts to only about 0.1 percent of the total solar energy reaching each ha during the year and equals about 3500 kg/ha of dry biomass. The amount of biomass varies with the crop and ranges from 200 kg/ha for low production crops under arid conditions to 15,000 kg/ha for corn and sugarcane.

    382. Which is the largest living bird on Earth?

    (1) Emu 
    (2) Ostrich
    (3) Albatross 
    (4) Siberian Crane
    382. (2) The Ostrich is the largest living species of bird and lays the largest egg of any living bird (extinct elephant birds of Madagascar and the giant moa of New Zealand did lay larger eggs). Ostriches usually weigh from 63 to 145 kilograms, Ostriches of the East African race averaged 115 kg in males and 100 kg in females, while the nominate subspecies was found to average 111 kg in unsexed adults.
    Exceptional male ostriches (in the nominate subspecies) have been weighing up to 156.8 kg. At sexual maturity (two to four years), male ostriches can be from 2.1 to 2.8 m in height, while female ostriches range from 1.7 to 2 m tall.

    383. In coriander, the useful parts are

    (1) roots & leaves
    (2) leaves & flowers
    (3) leaves & dried fruits
    (4) flowers & dried fruits
    383. (3) Coriander (Coriandrum sativum), also known as cilantro, Chinese parsley or dhania, is an annual herb in the family Apiaceae. All parts of the plant are edible, but the fresh leaves and the dried seeds are the parts most traditionally used in cooking. The fresh leaves are an ingredient in many South Asian foods (such as chutneys and salads), in Chinese dishes, in Mexican cooking, particularly in salsa and guacamole and as a garnish, and in salads in Russia and other CIS countries. Chopped coriander leaves are a garnish on Indian dishes such as dal. The dry fruits are known as coriander or coriandi seeds. In India they are called dhania. The word “coriander” in food preparation may refer solely to these seeds (as a spice), rather than to the plant. The seeds have a lemony citrus flavour when crushed, due to terpenes linalool and pinene.

    384. Which plant is called ‘Herbal Indian Doctor’ ?

    (1) Amla 
    (2) Mango
    (3) Neem 
    (4) Tulsi
    384. (1) The Indian gooseberry, or aamla from Sanskrit amalika, is a deciduous tree of the family
    Phyllanthaceae. It is known for its edible fruit of the same name. Although these fruits are reputed to
    contain high amounts of ascorbic acid (vitamin C), 445 mg/100g, the specific contents are disputed,
    and the overall antioxidant strength of amla may derive instead from its high density of ellagitannins such as emblicanin A (37%), emblicanin B (33%), punigluconin (12%) and pedunculagin (14%). It also contains punicafolin and phyllanemblinin A, B, C, D, E and F. There is preliminary evidence in vitro that its extracts induce apoptosis and modify gene expression in osteoclasts involved in rheumatoid arthritis and osteoporosis. It may prove to have potential activity against some cancers.

    385. The pH of human blood is

    (1) 7.2 
    (2) 7.8
    (3) 6.6 
    (4) 7.4
    385. (4) Different fluids in the human body generally have a delicate range of acid-alkaline balance they maintain for optimal functioning. Human blood has a normal pH of about 7.41. The pH of urine has a wider range. Normal ranges for urine pH are from 4.5 to 8. When the pH levels of blood or other key bodily fluids fall out of optimal pH range due to adverse metabolic or respiratory conditions, the human body goes through a variety of adjustments to try to correct the acid or alkaline imbalance. If the body is too alkaline, a condition called alkalosis results. Conversely, an overly acid condition results in acidosis.

    386. Which amongst the following is largest endocrine gland in the body ?

    (1) Thyroid
    (2) Parathyroid
    (3) Adrenal 
    (4) Pituitary
    386. (1) Endocrine glands are glands of the endocrine system that secrete their products, hormones, directly into the blood rather than through a duct. The main endocrine glands include the pituitary gland, pancreas, ovaries, testes, thyroid gland, and adrenal glands. The thyroid gland in vertebrate anatomy, is one of the largest endocrine glands. The thyroid gland is found in the neck, below the thyroid cartilage (which forms the laryngeal prominence, or “Adam’s apple”). The thyroid gland controls how quickly the body uses energy, makes proteins, and controls how sensitive the body is to other hormones. It participates in these processes by producing thyroid hormones, the principal ones being triiodothyronine (T3) and thyroxine which can sometimes be referred to as tetraiodothyronine (T4). These hormones regulate the rate of metabolism and affect the growth and rate of function of many other systems in the body. T3 and T4 are synthesized from both iodine and tyrosine. The thyroid also produces calcitonin, which plays a role in calcium homeostasis.

    387. Which amongst the following is the largest mammal ?

    (1) Elephant 
    (2) Whale
    (3) Dinosaur 
    (4) Rhinoceros
    387. (2) Blue whales are the largest animals ever known to have lived on Earth. These magnificent marine mammals rule the oceans at up to 100 feet (30 meters) long and upwards of 200 tons (181 metric tons). Their tongues alone can weigh as much as an elephant. Their hearts, as much as an automobile. Blue whales reach these mind-boggling dimensions on a diet composed nearly exclusively of tiny shrimplike animals called krill. During certain times of the year, a single adult blue whale consumes about 4 tons (3.6 metric tons) of krill a day.

    388. Which part becomes modified as the tusk of elephant ?

    (1) Canine
    (2) Premolar
    (3) Second incisor
    (4) Molar
    388. (3) Tusks are elongated, continuously growing front teeth, usually but not always in pairs, that protrude well beyond the mouth of certain mammal species. They are most commonly canines, as with warthogs, pig, and walruses, or, in the case of elephants, elongated incisors. In most tusked species both the males and the females have tusks although the males’ are larger.

    389. The noble gas used for the treatment of cancer is

    (1) Helium 
    (2) Argon
    (3) Krypton 
    (4) Radon
    389. (4) Radon was once commonly used to treat cancer. The radiation it gives off kills cancer cells. However, the element must be used with great care because radiation can kill healthy cells as well. In fact, the bad side-effects of radiation therapy are caused by the killing of healthy cells by radiation. Today, radon is not as widely used for the treatment of cancer. Radon is a radioactive element. A radioactive element is one that gives off radiation and breaks down to form a different element. Radon is formed when heavier radioactive elements, like uranium and thorium, break down. In turn, radon breaks down to form lighter elements, such as lead and bismuth.

    390. Bt seed is associated with

    (1) Rice 
    (2) Wheat
    (3) Cotton 
    (4) Oil seeds
    390. (3) Cotton is the most popular of the Bt crops: it was planted on about 1.8 million acres (728437 ha) in 1996 and 1997. The Bt gene was isolated and transferred from a bacterium bacillus thurigiensis to American cotton. The American cotton was subsequently crossed with Indian cotton to introduce
    the gene into native varieties. The Bt cotton variety contains a foreign gene obtained from bacillus
    thuringiensis. This bacterial gene, introduced genetically into the cotton seeds, protects the plants from bollworm (A. lepidoptora), a major pest of cotton. The worm feeding on the leaves of a Bt cotton plant
    becomes lethargic and sleepy, thereby causing less damage to the plant.

    391. Bark of this tree is used as a condiment–

    (1) Cinnamon 
    (2) Clove
    (3) Neem 
    (4) Palm
    391. (1) Cinnamon is a spice obtained from the inner bark of several trees from the genus Cinnamomum that is used in both sweet and savoury foods. The bark must be processed immediately after harvesting while still wet. Once processed, the bark will dry completely in four to six hours, provided that it is in a well-ventilated and relatively warm environment. Sri Lanka cinnamon has a very thin, smooth bark with a light-yellowish brown colour and a highly fragrant aroma.

    392. Saliva helps in the digestion of :

    (1) Fats 
    (2) Starch
    (3) Proteins 
    (4) Vitamins
    392. (2) Produced in salivary glands, saliva is 98% water, but it contains many important substances, including electrolytes, mucus, antibacterial compounds and various enzymes. The digestive functions of saliva include moistening food, and helping to create a food bolus, so it can be swallowed easily. Saliva contains the enzyme amylase that breaks some starches down into maltose and dextrin. Thus, digestion of food occurs within the mouth, even before food reaches the stomach.

    393. The longest bone in the human body is :

    (1) Ulna 
    (2) Humerus
    (3) Femur 
    (4) Tibia
    393. (3) The femur or thigh bone, is the most proximal (closest to the center of the body) bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in the rear legs. The femur is the largest bone in the human body. The head of the femur articulates with the acetabulum. By most measures the femur is one of the strongest bones in the body.

    394. Which of the following is the smallest bird?

    (1) Pigeon 
    (2) Parrot
    (3) Humming bird
    (4) House sparrow
    394. (3) Hummingbirds are birds that comprise the family Trochilidae. They are among the smallest of birds, most species measuring in the 7.5–13 cm (3–5 in) range. Indeed, the smallest extant bird species is a hummingbird, the 5-cm Bee Hummingbird. They can hover in mid-air by rapidly flapping their wings 12–80 times per second (depending on the species). They are known as hummingbirds because of the humming sound created by their beating wings, which sometimes sound like bees or other insects.

    395. White lung disease is prevalent among the workers of :

    (1) Paper industry
    (2) Cement industry
    (3) Cotton industry
    (4) Pesticide industry
    395. (*) White lung shows acute lung injury characterized by coughing and rales; inflammation of the lungs which become stiff and fibrous and cannot exchange oxygen. It occurs among persons exposed to irritants such as corrosive chemical vapors or ammonia or chlorine etc. Brown lung, or bysinnois, similar to black lung (pneumoconiosis) and white lung (asbestosis) disease among coal miners and shipyard workers exposed to asbestos are well known occupational hazars.

    396. Iodoform is used as an :

    (1) antipyretic 
    (2) analgesic
    (3) antiseptic 
    (4) anaesthetic
    396. (3) Iodoform is the organoiodine compound with the formula CHI3. A pale yellow, crystalline, volatile substance, it has a penetrating odor and, analogous to chloroform, sweetish taste. It is occasionally used as a disinfectant. Around the beginning of the 20th century it was used in medicine as a healing and antiseptic dressing for wounds and sores, although this use is now superseded by superior antiseptics. Adolf Hitler’s mother, Klara Hitler, died of iodoform poisoning brought on by her treatment for breast cancer. It is the active ingredient in many ear powders for dogs and cats, to prevent infection and facilitate removal of ear hair, along with zinc oxide and propanoic acid.

    397. The optimum dissolved oxygen level (in mg/litre) required for survival of aquatic organisms is :

    (1) 4 – 6 
    (2) 2 – 4
    (3) 8 – 10 
    (4) 12 – 16
    397. (1) Oxygen is one of several dissolved gases important to aquatic systems. Dissolved oxygen is necessary to maintain aerobic conditions in surface waters and is considered a primary indicator when assessing the suitability of surface waters to support aquatic life. For maintenance of aquatic health, dissolved oxygen concentrations should approach saturation – that concentration which is in equilibrium with the partial pressure of atmospheric oxygen. Dissolved oxygen can be measured in two ways: either in milligrams per liter (mg/L) or percent saturation (% sat). Water with an oxygen concentration of less than 3 mg/l will generally not support fish. When concentrations fall to about 3-4 mg/L, fish start gasping for air at the surface or huddle around the water fall (higher concentration points). Bio-converter bacteria may start to die off dumping toxins into the water compounding the lack of oxygen to the fish. Levels between 3 and 5 mg/l can normally be tolerated for short periods. Young Koi are less tolerant of low oxygen than the older, larger ones. Above 5 mg/l, almost all aquatic organisms can survive indefinitely, provided other environmental parameters are within allowable limits. Colder water fish (such as trout) need levels above 6 mg/L, and may require levels above 7 mg/L for spawning. Warm water fish can usually tolerate levels as low as 4 mg/L. If oxygen levels dip down to 1-2 mg/L, even only for a few hours, it can result in large fish kills.

    398. An example of false fruit is

    (1) Apple 
    (2) Guava
    (3) Mango 
    (4) Tomato
    398. (1) An accessory fruit (sometimes called false fruit, spurious fruit, pseudofruit, or pseudocarp) is a fruit in which some of the flesh is derived not from the ovary but from some adjacent tissue exterior to the carpel. Examples of accessory tissue are the receptacle of strawberries, figs, or mulberries, and the calyx of Gaultheria procumbens or Syzygium jambos. Pomes, such as apples and pears, are also accessory fruits, with much of the fruit flesh derived from a hypanthium. Fruit with fleshy seeds, such as pomegranate or mamoncillo, are not considered to be accessory fruit.

    399. Normal fasting blood sugar level per 100 ml. of blood in man is

    (1) 30 - 50 mg
    (2) 50 - 70 mg
    (3) 80 -100 mg
    (4) 120 -140 mg
    399. (3) The blood sugar concentration or blood glucose level is the amount of glucose (sugar) present in the blood of a human or animal. The body naturally tightly regulates blood glucose levels as a part of metabolic homeostasis. The mean normal blood glucose level in humans is about 4 mM (4 mmol/L or 72 mg/dL, i.e. milligrams/deciliter); however, this level fluctuates throughout the day. Glucose levels are usually lowest in the morning, before the first meal of the day (termed “the fasting level”), and rise after meals for an hour or two by a few millimolar. Normal Human Glucose Blood Test results should be 70 - 130 (mg/ dL) before meals, and less than 180 mg/dL after meals (as measured by a blood glucose monitor). Less than 100 mg/dl (milligrams per deciliter) = normal fasting glucose. More than 100 but less than 126 mg/dl = pre-diabetes. More than 126 mg/dl = provisional diagnosis of diabetes.

    400. The vector of disease sleeping sickness is

    (1) sand-fly 
    (2) house-fly
    (3) fruit-fly 
    (4) tse-tse fly
    400. (4) Human African trypanosomiasis, sleeping sickness, African lethargy, or Congo trypanosomiasis is a parasitic disease of people and animals, caused by protozoa of the species Trypanosoma brucei and transmitted by the tsetse fly. It results in swelling of the brain. The disease is endemic in some regions of sub-Saharan Africa, covering areas in about 37 countries containing more than 60 million people. An estimated 50,000 to 70,000 people are currently infected, the number having declined somewhat in recent years. The tsetse fly is a large, brown, biting fly that serves as both a host and vector for the trypanosome parasites.

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