Biology MCQ Quiz - Objective Question with Answer for Biology - Download Free PDF

The Correct answer is Increased saliva and digestion.

Key Points

• Chewing food thoroughly stimulates the production of saliva, which contains enzymes like amylase and lipase that aid in the breakdown of carbohydrates and fats.
• Saliva not only helps in digestion but also moistens the food, forming a bolus, which makes it easier to swallow and pass through the esophagus.
• Proper chewing enhances the breakdown of food into smaller particles, which increases the surface area for digestive enzymes to act upon in the stomach and intestines, improving overall digestion.
• Mindful eating, which involves chewing thoroughly, allows the brain to register satiety signals, reducing the likelihood of overeating and supporting healthy weight management.
• Chewing thoroughly reduces the risk of indigestion and bloating as it ensures food is adequately processed before it reaches the stomach.
• It promotes better absorption of nutrients by ensuring the food is broken down effectively, facilitating easier digestion and assimilation in the small intestine.
• Chewing stimulates the production of gastric juices in the stomach, further aiding the digestive process.
• Mindful eating and thorough chewing can also enhance the sensory experience of eating, allowing individuals to savor flavors, textures, and aromas more deeply.

Additional Information

• Faster eating
  • Faster eating often leads to overeating because the brain does not have enough time to process satiety signals, resulting in delayed recognition of fullness.
  • It can cause digestive issues like bloating, gas, and indigestion because food is not adequately chewed.
• Increased calorie intake
  • Chewing food thoroughly during mindful eating generally helps reduce calorie intake as it promotes a sense of fullness, contrary to this option.
  • Increased calorie intake is often associated with unmindful or rushed eating practices.
• Reduced nutrient absorption
  • Chewing food thoroughly actually enhances nutrient absorption because it facilitates better digestion and breakdown of food particles.
  • Reduced nutrient absorption can occur if food is swallowed without proper chewing, leading to incomplete digestion.

The correct answer is option 3.

Key Points

• Human insulin was the first hormone to be produced using recombinant DNA technology. Hence, option 3 is correct.
• It was developed by Genentech and Eli Lilly in the early 1980s, marking a major breakthrough in biotechnology and medicine.
• This synthetic insulin is called "Humulin", and it is produced by inserting the human insulin gene into E. coli bacteria, which then synthesize insulin.

Key Points

• Polyembryony refers to the occurrence of more than one embryo in a single seed.
• It is commonly observed in Citrus fruits, such as oranges and lemons.
• In Citrus, polyembryony often occurs due to the development of nucellar embryos along with the zygotic embryo.
• Polyembryony ensures the production of genetically uniform plants, which is beneficial for agriculture.

Important Points

• In plants exhibiting polyembryony, multiple embryos can develop from the same ovule, resulting in more plants from a single seed.
• Polyembryony can be classified into three types:
  • Simple polyembryony: Development of multiple embryos from a single zygote.
  • Adventive polyembryony: Development of embryos from somatic cells of the ovule (e.g., nucellar tissue).
  • Mixed polyembryony: Involves both zygotic and adventive embryos.

Additional Information

• Banana: Bananas are parthenocarpic fruits, meaning they develop without fertilization. They do not exhibit polyembryony.
• Tomato: Tomato plants reproduce sexually, and their seeds usually develop a single embryo. Polyembryony is not observed in tomatoes.
• Potato: Potatoes are propagated vegetatively through tubers. They do not involve seeds and hence do not exhibit polyembryony.

Key Points

• Synergids are two specialized cells located in the embryo sac of a flowering plant.
• They play a crucial role in guiding the pollen tube to the egg cell for fertilization.
• They release chemical signals to attract the pollen tube, ensuring successful fertilization.
• Once the pollen tube reaches the synergids, one synergid degenerates to facilitate the release of sperm cells for fertilization.

Important Points

• The synergids are part of the egg apparatus in the ovule and are located near the micropyle.
• They assist in breaking down barriers so the sperm cells can reach the egg cell and central cell.
• They are necessary for the precise delivery of male gametes to the female gametophyte.
• Synergids also help sustain the pollen tube during its growth process.
• Micropyle: The micropyle is the opening in the ovule through which the pollen tube enters to deliver sperm cells to the egg apparatus.

• Embryo sac: The embryo sac is the female gametophyte in angiosperms, containing the egg cell, synergids, central cell, and antipodal cells.

Key Points

• Appearance of hair on the head of a human embryo typically occurs during the 5th month of pregnancy.
• By the 5th month, the embryo develops lanugo, which is fine, soft hair that covers the body, including the head.
• Lanugo plays a crucial role in helping to regulate the fetus’s body temperature within the womb.
• This hair gradually disappears before birth or shortly after birth, as it is replaced by vellus or terminal hair.

Important Points

• The development of hair follicles begins early in the embryonic stage, but visible hair growth on the head starts during the 5th month.
• The growth of hair is part of the overall development of the fetus, including skin and appendages.
• Lanugo is a temporary protective mechanism for the fetus and is not permanent.
• Proper fetal development during this phase is crucial and can be influenced by maternal nutrition, health, and genetics.

Concept:

• Thermoregulation is the mechanism by which some animals like mammals maintain their core body temperature irrespective of the changing environmental temperature.
• Based on whether an animal can maintain their body temperature or not they are divided into two: Homeotherm and Poikilotherms.

1. Homeotherm: An animal that can maintain constant internal body temperature. Birds and mammals are homeotherms.
2. Poikilotherm: An animal that cannot maintain a constant internal body temperature. The internal temperature in these animals varies generally with the varying environmental temperatures. Amphibians and reptiles are poikilotherms.

Explanation:

• Frogs are poikilotherms i.e. they cannot maintain a constant body temperature.
• Their body temperature fluctuates with that of the environment.
• During winters, the frog's body temperature becomes too low. As a result of which all the body activities of the frog get ceased and it becomes sluggish.
• Similarly during summers, due to high temperatures again the body's activities cease and the animal becomes sluggish.
• To avoid such harsh environmental conditions, frogs undergo special adaptations that enable them to survive in unfavorable conditions.
• Hibernation and Aestivation are the two adaptations taken up by the frog to avoid unfavorable conditions.

HIBERNATION:

• Hibernation is also known as winter sleep.
• During winters, frogs dig deep down into damp earth at the bottom of the ponds and rest there.
• During hibernation, lung breathing is stopped in the frog.
• The skin continues breathing which suffices the oxygen requirement of the frog during hibernation.

AESTIVATION:

• Aestivation is also known as summer sleep.
• Just like in hibernation, during aestivation too frogs burrow themselves into the damp earth.
• On the arrival of the rainy season, the animal resumes its normal body activities.

So from the above-given information, the correct answer is option 4 (Skin only).

Additional Information

•  Ectotherm: Ectotherms rely on the external environment to regulate their body temperature. These are also called cold-blooded animals. Poikilotherms are regarded as ectotherms.
• Endotherm: Endotherms are animals that maintain their own body temperature through metabolic activities. These are also called warm-blooded animals. Homeotherms are regarded as endotherms.

The correct answer is autotrophic nutrition.Key Points

• Autotrophic nutrition is the mode of nutrition in which organisms make their food themselves from simple substances.
• The process of autotrophic nutrition involves the use of light energy (in photosynthesis) or chemical energy (in chemosynthesis) to produce organic compounds.
• Autotrophs are organisms that carry out autotrophic nutrition, such as plants, algae, and some bacteria.

Additional Information

• Heterotrophic nutrition is the mode of nutrition in which organisms obtain their food by consuming other organisms or organic matter.
• Saprotrophic nutrition is a type of heterotrophic nutrition in which organisms obtain their food by decomposing dead organic matter.
• Phototrophic nutrition is a subcategory of autotrophic nutrition, in which organisms use light energy to produce their own food.

The correct answer is i - b, ii - c, iii - d, iv - a.

Key Points

The trophic levels represent the hierarchical levels in an ecological food chain, indicating the position of organisms based on their feeding relationships. Here's the explanation for the correct match:

• First trophic level - phytoplankton:
  • The first trophic level typically consists of primary producers that convert sunlight into energy through photosynthesis.
  • Phytoplankton are microscopic plants that form the base of aquatic food chains.
• Second trophic level - zooplankton:
  • The second trophic level comprises primary consumers that feed on the primary producers.
  • Zooplankton, which includes tiny animals, consume phytoplankton, placing them at the second trophic level.
• Third trophic level - fishes:
  • The third trophic level involves secondary consumers that feed on primary consumers.
  • In aquatic ecosystems, fishes are often positioned at the third trophic level as they consume zooplankton or other smaller organisms.
• Fourth trophic level - human:
  • The fourth trophic level represents tertiary consumers, which are higher-order predators.
  • Humans, being omnivores or carnivores, are often placed at the fourth trophic level in food chains when they consume animals from lower trophic levels.​ 

The correct answer is a - iv, b - iii, c - ii, d - i.

Key Points

• Blue-green Algae (Cyanobacteria)
  • Blue-green algae are actually bacteria and are also known as Cyanobacteria.
  • They are photosynthetic organisms and can live in a wide variety of environments, including freshwater, seawater, damp soil, or rocks.
  • Cyanobacteria are known for their significant contribution to the Earth's oxygen atmosphere.
  • They can exist as single cells or can form colonies.
• Red Algae (Rhodophyta)
  • Red algae, often called Rhodophyta, have been identified as one of the oldest groups of eukaryotic algae.
  • They are mostly found in the warmer waters of the ocean.
  • Red algae are of great economic value because of their use in the production of agar and carrageenan, substances used as thickening agents in various food products.
  • Their red colour is due to the pigment, phycoerythrin.
• Green Algae (Chlamydomonas)
  • Green algae are a diverse group of algae from which plants evolved. Chlamydomonas is a genus of unicellular green algae.
  • Chlamydomonas species are widely distributed worldwide and are found in soil and freshwater.
  • They have two flagella that allow them to move.
  • They are known for their green colour due to the presence of chlorophyll.
• Brown Algae (Sargassum)
  • Brown algae are the most complex type of algae; many are seaweeds.
  • Sargassum is a brown algae, known for forming massive floating forests in the ocean.
  • It is primarily marine and is found in warm-temperate and tropical oceans.
  • They provide important ecological functions such as providing habitats for a wide variety of marine species.
  • The brown colour is due to the presence of a pigment called fucoxanthin, which masks the green colour of chlorophyll.

Concept: 

• Fruit refers to a mature or ripened ovary, developed after fertilization.
• The fruit consists of a wall or pericarp and seeds.
• When the pericarp is thick and fleshy, it is differentiated into the outer epicarp, the middle mesocarp, and the inner endocarp. 

Explanation:

• Fruit is said to be false fruit when the fruit is formed from the other parts of the flower as well as the ovary like the receptacle (base), the perianth, thalamus, inflorescence, or calyx.

• Examples of such fruits are strawberries, pineapple, mulberry, apples, pears, etc.

• The given figure is of a false fruit.

• False fruit develops from other floral parts and the thalamus along with the development of the ovary wall.

• Therefore, the correct answer is option 4.

Additional Information If the fruit is formed without fertilization of the ovary, it is called a parthenocarpic fruit.

The correct answer is Collar cells.

 Key Points

• The body of sponges (poriferans) has several minute pores called ostia through which the water enters into the central cavity, spongocoel.
• The flagellated cells called choanocytes (collar cells) line the spongocoel.
• These cells generate a flow of water and the water current helps in food gathering, respiratory exchange and removal of waste.
• The water finally goes out of the body through a large pore called osculum. (Plural: oscula).
• The body wall of the sponge is composed of two layers: outer pinacoderm and inner choanoderm. In between these two layers, mesenchyme is present with various mesenchymal cells.

Additional Information

• Somatic cells make up the connective tissue, skin, blood, bones and internal organs.
• White blood cells are made in the bone marrow. They are stored in your blood and lymph tissues.
• These sex cells are also called reproductive cells or gametes. Sperm cells are produced in men's testicles and egg cells are produced in women's ovaries

The correct answer is Rhodophyceae.Key Points

• Red algae:-
  • It is a type of marine algae that are predominantly red in color due to the presence of pigments such as phycoerythrins and phycocyanins.
  • They are found in both tropical and temperate waters and play an important role in marine ecosystems as primary producers and as a food source for herbivorous marine animals.
  • Some species of red algae are also used by humans for various purposes such as food, medicine, and cosmetics.
  • Red algae are known for their ability to survive in extreme environments such as deep-sea hydrothermal vents and polar regions.

Additional Information

• Chlorophyceae:
  • This is a class of green algae that are mostly freshwater species and are commonly found in ponds, lakes, and streams.
• Liverwort:
  • This is a type of non-vascular plant that grows in damp habitats such as forests, bogs, and riverbanks.
  • They are commonly found in temperate and tropical regions and play an important role in soil formation and nutrient cycling.
• Phaeophyceae:
  • This is a class of brown algae that are predominantly marine and are commonly found in temperate and cold waters.
  • They are important primary producers in coastal ecosystems and are also used by humans for food and other purposes.

The correct answer is i - b, ii - a, iii - c, iv - d

Key Points

• The cell physically expands, duplicates organelles, and creates the molecular building blocks it will require in subsequent stages during G1phase, also known as the first gap phase.
• The cell creates a full copy of the DNA in its nucleus during the S phase. Moreover, it makes duplicates of the centrosome, a structure that organises microtubules. During M phase, the centrosomes aid in the separation of DNA.
• The second gap phase, also known as the G2 phase, is a time of increased cell growth, protein and organelle production, and content reorganisation in preparation for mitosis.
• The cell's nuclear DNA condenses into its visible chromosomes during mitosis and is separated by the mitotic spindle, a specialised microtubule-based structure.

Additional Information

•  Stages of the cell cycle
  • ​A cell must grow, replicate its genetic material (DNA), and physically split into two daughter cells before it may divide.
  • The cell cycle is a structured, predictable series of actions that cells take to complete these goals.
  • Because the two daughter cells can restart the entire process from the beginning after each cycle, the cell cycle is a cycle rather than a linear pathway.

The correct answer is Ground tissue.

• The term cortex refers to the outermost layer of a structure.
• In the brain, the cortex most often refers to the cerebral cortex, although the cerebellum also has an outer layer called the cerebellar cortex.
• The three types of ground tissue: parenchyma, collenchyma, and sclerenchyma.
  • A function included photosynthesis, storage, regeneration, support, and protection.

Important Points

Additional Information

The correct answer is Marchantia.Key Points

• Liverworts:-
  • These are non-vascular plants that belong to the phylum Hepatophyta.
  • The umbrella-shaped structures that raise gametangia above the main gametophyte body are known as archegoniophores.
  • These archegoniophores are found in the genus Marchantia.
• Marchantia:-
  • It is a genus of liverworts, which are a type of non-vascular plant often found in moist and damp environments.
  • Liverworts belong to the division Marchantiophyta and are some of the earliest land plants to have evolved.
  • Marchantia liverworts are small, flat, and leafy plants that typically grow in low, spreading mats.
  • They have a distinctive appearance with flattened, lobed structures that resemble tiny leaves.

Additional Information

• Polytrichum:-
  • It​ also known as haircap moss, is a type of moss that forms dense cushions or tufts in moist habitats.
• Funaria:-
  • It​ is also known as cord moss, is a common type of moss that is found in moist, shaded habitats.
• Sphagnum:-
  • It is  also known as peat moss, is a type of moss that is found in wetlands and bogs and is known for its ability to store water.