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

Answer:
B) An eye disorder caused by prolonged Vitamin A deficiency

Key Points

• Caused by Vitamin A deficiency 
• Leads to dryness of eyes
• Cornea becomes opaque
• Can cause night blindness
• Common in malnourished children

Important Points

• Preventable with Vitamin A supplementation
• Promoted by WHO in deficiency-prone areas
• If untreated, leads to permanent blindness

Additional Information

• Vitamin A sources: carrots, spinach, liver, dairy
• Also affects immunity and growth
• Major public health concern in developing countries

Answer:
Correct Answer: B) Gregor Johann Mendel

Key Points

• Mendel conducted hybridization experiments on pea plants.
• He discovered that traits are inherited in specific ratios. 
• His work laid the foundation for modern genetics.
• He was an Austrian monk and scientist.
• His contributions were initially overlooked but later became the basis of classical genetics.

Additional Information

• Charles Darwin is known for the theory of evolution.
• Watson and Crick discovered the double-helix structure of DNA in 1953.
• Lamarck proposed an early theory of evolution based on the inheritance of acquired characteristics, which was later disproven.

Answer:
B) Adenine, Guanine, Uracil, Cytosine

Key PointsRNA (Ribonucleic Acid) is made up of four nitrogenous bases:

• Adenine (A)
• Guanine (G)
• Cytosine (C)
• Uracil (U)

In RNA, Uracil (U) replaces Thymine (T), which is found in DNA.

RNA is typically single-stranded, unlike DNA, which is double-stranded.

Important PointsBase Pairing in RNA:

• Adenine (A) pairs with Uracil (U)
• Guanine (G) pairs with Cytosine (C)

Key Points

Discoverers:

• James Watson (American biologist)
• Francis Crick (British physicist)
• Proposed the double helix model of DNA in 1953.

Model:

• DNA consists of two strands twisted into a double helix.
• The strands are held together by complementary base pairs:
• Adenine (A) pairs with Thymine (T)
• Cytosine (C) pairs with Guanine (G)

Nobel Prize:

• In 1962, the Nobel Prize in Physiology or Medicine was awarded to:
• James Watson, Francis Crick, and Maurice Wilkins
• Rosalind Franklin's crucial contributions were not recognized at the time due to her early death in 1958.

The correct answer is Cerebellum.

Key Points

• The cerebellum is located at the back of the brain, underneath the occipital lobes.
• It plays a crucial role in motor control, particularly in coordinating voluntary movements.
• The cerebellum helps maintain balance and posture by integrating sensory information from the spinal cord and other parts of the brain.
• It is involved in motor learning, allowing the body to perform smooth, accurate, and balanced movements.
• Damage to the cerebellum can result in ataxia, which is characterized by a lack of coordination and control over movements.

Additional Information

• Cerebrum
  • The cerebrum is the largest part of the human brain and is responsible for higher brain functions such as thought, action, and sensory processing.
  • It is divided into two hemispheres, each of which is further divided into lobes responsible for different functions.
  • The cerebrum controls voluntary muscle movements and is involved in cognitive functions like learning and memory.
• Medulla
  • The medulla oblongata is located in the brainstem and controls autonomic functions like breathing, heart rate, and blood pressure.
  • It acts as a relay station, transmitting signals between the brain and the spinal cord.
• Hypothalamus
  • The hypothalamus is a small region located below the thalamus and is crucial for maintaining homeostasis in the body.
  • It regulates various autonomic functions such as temperature control, hunger, thirst, and circadian rhythms.
  • The hypothalamus also plays a role in hormone secretion through its interaction with the pituitary gland.

The correct answer is Protein synthesis.

Key Points

• Ribosomes are membranous granular structures present in the cytoplasm.
• They were first observed under an electron microscope as dense particles by George Palade in the year 1953.
• Ribosomes are the site for ''protein synthesis'' so they are also called the ''protein factory'' of the cell.
• There are two types of ribosomes

1. Eukaryotic ribosomes - 80s - occurs in the cytoplasm of eukaryotic cell
2. Prokaryotic ribosomes - 70s - occur in the cytoplasm as well as are associated with the cell membrane of prokaryotic cell.

• The subunits of the ribosomes are:
  • 80s ribosomes - are made of 60s and 40s subunits.
  • 70s ribosomes - are made of 50s and 30s subunits.

Important Points

• Composition of the structure of ribosome:
• They are composed of ribonucleic acid (RNA) and proteins

Additional Information

• Photosynthesis: It is the process by which green plants and some other organisms use sunlight to synthesize nutrients from carbon dioxide and water. In this process, plant the chlorophyll, carbon dioxide, water, sunlight, and release oxygen.
• Synthesis of Fatty acids occurs in the cytoplasm.

The correct answer is Bile juice, Pancreatic juice.

Key Points

• Bile juice, Pancreatic juice secreted by the organs plays an important role in the digestion of fats.
• Bile juice is secreted by the liver.
  • It does not contain any types of enzymes.
  • The bile juice helps to make the food alkaline and break down the fat molecules.
• Pancreatic juice is secreted by the pancreas.
  • It contains enzymes like amylase, trypsin, pancreatic lipase, nucleases and lipase.
  • Secretion of the Pancreatic juice is regulated by the hormones secretin and cholecystokinin.
• Lipase is the digestive enzyme of fat.
• Ptyalin is the digestive enzyme of the Saliva.
• Hydrochloric acid is produced naturally in the human stomach to help the digestion of food.

Concept:

Photosynthesis: 

• The leaves have a green pigment called chlorophyll.
• It helps leaves to capture the energy of the sunlight.
• This energy is used to synthesise (prepare) food from carbon dioxide and water. Since the synthesis of food occurs in the presence of sunlight, it is called photosynthesis.

In the presence of sunlight Carbon dioxide + water → Carbohydrate + oxygen.

• Some plants, green algae, and cyanobacteria can perform photosynthesis.
• The process of photosynthesis is commonly written as

                   6CO2 + 6H2O + Sun-Light → C6H12O6 + 6O2

Plant cells have a cell wall to protect them and make them rigid structure.

Explanation:

1. Plants convert energy from sunlight into food stored as carbohydrate’s - Correct

2. Plants have chlorophyll. - Correct

3. Plant cells do not have cell walls. - Incorrect.

Additional Information

In the plant cells, there are different components and organelles for specific functions-

• Cell Wall – It is a rigid layer composed of cellulose. It is the outermost layer of the cell, below this cell membrane is present. The primary function of the cell wall is to protect and provide structural support to the cell.
• Cell Membrane – It is a semi-permeable membrane that helps in regulating and the substance for entry and exit inside and outside the cell.
• Nucleus – It is a vital part of the cell as it contains all the information or DNA of the cell and their heredity information for growth and cell division.
• Vacuole – Most of the part of the plant cell is occupied by the vacuole. It is surrounded by Tonoplast. The vital role of the vacuole is to provide support again the pressure of the cell wall.
• Golgi apparatus – They act as a transport system in the cell, as they transport various molecules to a different part of the cell.
• Ribosomes – They are the sites of protein synthesis, also termed as the protein factory of the cell.
• Mitochondrion – They break the complex molecules and produce energy and hence called the powerhouse of the cell.
• Lysosomes – They are termed suicidal bags as they hold the enzymes that are capable to digest the whole cell itself.

The correct answer is Whale.

Key Points

• Gills are respiratory organs found in most aquatic organisms.
• Gills can extract dissolved oxygen from water and excrete carbon dioxide.
• Gills can be found in Octopus, Squid, Clownfish, Tadpole, Prawn, etc.
• Lungs are the breathing organ of Whales.

Additional InformationRespiratory organs of different Animals:

The correct answer is Both chloroplast and mitochondria

Concept:

Theory of endosymbiosis:-

• Symbiotic relationship, where one organism lives inside the other, is known as endosymbiosis. 
• The theory proposed that mitochondria and chloroplasts evolved from engulfed prokaryotes.
• A large anaerobic bacteria engulfed an aerobic prokaryote, which then formed an endosymbiotic relationship with the host, gradually developing into a mitochondrion.
• It is believed that chloroplasts originated from a cyanobacterial endosymbiont.

Explanation:

Similarities between Prokaryotic cells, Mitochondria, and Chloroplast:

• Mitochondria and chloroplast are of the same size as prokaryotic cells.
• Mitochondria and prokaryotic cells both have their own circular DNA.
• The ribosome of bacteria, mitochondria, and chloroplasts have a 70S type of ribosome.
• Divides by binary fission.

• Vitamin K is a vitamin found in leafy green vegetables, broccoli, and Brussels sprouts.
• In the body, vitamin K plays a major role in blood clotting. So it is used to reverse the effects of “blood-thinning” medications when too much is given; to prevent clotting problems in newborns who don’t have enough vitamin K, and to treat bleeding caused by medications.

Tricks:

The correct answer is Cellulose.

• Plant cell walls are primarily made of cellulose.

Key Points

• Cellulose is the most abundant macromolecule on Earth.
  • Cellulose fibers are long, linear polymers of hundreds of glucose molecules.
  • These fibres aggregate into bundles of about 40, which are called microfibrils.

Additional Information

• Carbohydrates are the sugars, starches, and fibres found in fruits, grains, vegetables, and milk products.
  • A carbohydrate is a biomolecule consisting of carbon (C), hydrogen (H), and oxygen (O) atoms.
• Lipids are molecules that contain hydrocarbons and make up the building blocks of the structure and function of living cells.
  • A lipid is a biomolecule that is soluble in nonpolar solvents.
• A lipoprotein is a biochemical assembly whose primary function is to transport hydrophobic lipid also known as fat molecules in water, as in blood plasma or other extracellular fluids.
  • It consists of a Triglyceride and Cholesterol centre, surrounded by a phospholipid outer shell, with the hydrophilic portions oriented outward towards the surrounding water and lipophilic portions oriented inward toward the lipid centre.

The correct answer is Collenchyma.

 Concept:

• Collenchyma is a specialized simple permanent tissue that provides support and flexibility to plants.
  • This tissue is made up of living cells having uneven thickenings of cellulose, pectin, and hemicellulose on the walls.
  • Cells possess chloroplast, then it is involved in manufacturing sugar and starch.
  • Provides tensile strength and flexibility to the plant body.

Explanation:

• Parenchyma- this tissue provides support to plants. It also stores food. So this option is not correct.

• Collenchyma- it allows easy bending of plant parts and provides flexibility. So the option is correct.
• Sclerenchyma- this tissue makes the plant hard and stiff. It is present in the husk of a coconut. So the option is not correct.

Additional Information

• Parenchyma is the most common and abundant tissue in plants which is made up of thin-walled living cells having a distinct nucleus.
  • The main function of parenchyma is to store and assimilate food. Hence, they are referred to as food storage tissues.
  • Serves as a packing tissue to fill the spaces between other tissues and maintain the shape and firmness of the plant.
  • Stores waste products of plants.
• Sclerenchyma is a lignified supportive tissue made up of thick-walled and lignified cells.
  • Provides mechanical strength to the plant.

Influenza disease is caused by a Virus.

Trick: Virus influence many Diseases