Tag: biology

Questions Related to biology

Which one of the following organisms may respire in the absence of oxygen?

  1. Azotobacter

  2. Clostridium

  3. Rhizobium

  4. Lactobacillus


Correct Option: B
Explanation:

Obligate anaerobic beings are those that cannot survive when oxygen is present. Some fungi, some bacteria (like the agent of botulism -Clostridium botulinum, and the agent of tetanus- Clostridium tetani) and some protozoans are examples of obligate anaerobes.


For aerobic respiration to occur

  1. Pyruvate must be transported to the mitochondrion

  2. Oxygen must be available to the mitochondrion

  3. Hydrogen ions released from the breakdown of pyruvate must be carried to the electron transport system

  4. All of the above


Correct Option: D
Explanation:

  • Aerobic respiration is the process that takes place in the presence of oxygen.
  • The first part of the process is where the molecule of glucose is broken down to 2 molecules of pyruvate by the process of glycolysis
  • These pyruvate molecules are to enter the mitochondria to under go the reaction of kerb cycle, but the molecule of pyruvate itself cannot enter the mitochondria, it is converted to acetyl CoA so that it can enter inside the mitochondrion membrane.
  • After the kerb cycle molecules of NADH and $FADH _2$are formed which enter the ETS and undergo oxidative phosphorylation.
  • Hydrogen ions are released from the NADH and $FADH _2$ molecules which are transported from inner membrane of mitochondria to the intermembrane matrix of mitochondria, this builds a concentration gradient across the membrane. Also the hydron ions and the electrons that are transported by the complexs of the ETS are in the end accepted by the oxygen molecule forming water that is why it is known as oxidative phosphorylation
  • The concentration gradient that is made is used for the transport of hydronium ions across the ATP synthase complex of the inner mitochrondrial membrane. 
  • With the transport of 2 hydrogen ions one molecule of ATP is formed.
  • Thus glycolysis which takes place in cytoplasm, Kerb cycle that takes place in mitochondria , oxidative phosphorylation and chemisomotic phosphorylation are the parts of aerobic respiration.
  • Therefore the answer 'All of the above' is correct.

















CAM plants are mostly

  1. Tropical plants

  2. Succulents

  3. Monocots

  4. Mangroves


Correct Option: B
Explanation:

CAM (Crassulacean Acid Metabolism) is a pathway of photosynthesis which occurs in desert succulents, which have a low surface-to-volume ratio. In this pathway of photosynthesis carbon is fixed during night time while decarboxylation reaction takes place at day time..

So, the correct option is 'succulents'

X is one of the important components of food. Wheat, pearl millet and sweet potato are rich sources of X, X gives a blue-black colour with a dilute solution of iodine. Identify X.

  1. Minerals

  2. Fats

  3. Proteins

  4. Carbohydrates


Correct Option: D
Explanation:

  • Starch gives blue-black colour with Iodine and is used as a test. Starch is a polysaccharide(carbohydrate).

So, the correct option is 'Carbohydrates'.

Which of the following organs contain(s) smooth muscles?

  1. Blood vessels

  2. Iris of the eye

  3. Bronchi

  4. All of the above


Correct Option: D
Explanation:

Smooth muscles are spindle-shaped and are under involuntary control. They are seen in the internal organs such as the blood vessels, iris and the lung bronchi. In the blood vessels, they enable the blood flow. In iris, they increase the pupil size in the presence of bright light. They help in lung contraction and relaxation due to their presence in bronchioles. Thus the correct answer is option D.

Which of the following tissues is made up of long contractile cells packed with actin and myosin microfilaments?

  1. Epithelial tissue

  2. Adipose tissue

  3. Fibrous connective tissue

  4. Nervous tissue

  5. Muscle tissue


Correct Option: E
Explanation:

Muscles contract via the action of proteins actin and myosin. Both these proteins are present as microfilaments. Actin forms the thin filaments of muscle cells and myosin forms the thick filaments.

So, the correct answer is 'Muscle tissue'.

Myology is the study of

  1. Muscles

  2. Bones

  3. Cartilages

  4. None of the above


Correct Option: A
Explanation:

"Myo" refers to "Muscles". Myology is the study of the muscular system, including the study of the structure, function, and diseases of muscle.