Category: Class 11 Biology Objective Questions

250+ TOP MCQs on Human Excretory System and Answers

Biology Multiple Choice Questions on “Human Excretory System – 1”.

1. Which of the following is not included in the excretory system of humans?
a) Cloaca
b) Kidneys
c) Ureters
d) Urethra
Answer: a
Clarification: In humans, the excretory system consists of a pair of kidneys, one pair of ureters, a urinary bladder, and urethra. Kidneys are reddish-brown and bean-shaped structures.

2. Where are the kidneys situated?
a) Between the 7th and 10th ribs
b) Between the last thoracic and third lumbar vertebra
c) Between the 8th and 9th ribs
d) Between the first and second thoracic vertebra
Answer: b
Clarification: Kidneys are reddish-brown, bean-shaped structures situated between the levels of the last thoracic and third lumbar vertebra close to the dorsal inner wall of the abdominal cavity.

3. What is the average weight of a human kidney?
a) 40 g
b) 100 g
c) 120 g
d) 10 g
Answer: c
Clarification: Each kidney of an adult human measures for about 10-12 cm in length, 5-7 cm in width, and 2-3 cm in thickness with an average weight of 120-170 grams.

4. Through which of the following nerves and blood vessels enter the kidneys?
a) Hilum
b) Tubules
c) Pelvis
d) Medulla
Answer: a
Clarification: Through the hilum, the nerves, the ureters and the blood vessels enter the kidneys. The hilum is a notch which is present towards the centre of the inner concave surface of the kidney.

5. Inside the kidney, there are three zones.
a) True
b) False
Answer: b
Clarification: The outer layer of the kidney is a tough capsule. Inside the kidney, there are two zones, an outer cortex, and an inner medulla. Inner to the hilum, a broad funnel-shaped space is presently called the renal pelvis.

6. Which of the following is responsible for the formation of Columns of Bertini?
a) Medulla
b) Renal pelvis
c) Calyces
d) Cortex
Answer: d
Clarification: Cortex is mainly responsible for the formation of columns of Bertini. The portion of the cortex which extends in between the medullary pyramids as renal columns form the columns of Bertini. The medulla region of the kidney is divided into a few conical masses called medullary pyramids which project into the calyces.

7. Which of the following is incorrectly marked in the given diagram?

a) Renal artery and inferior vena cava
b) Hepatic portal vein and sebaceous gland
c) Dorsal aorta and ureter
d) Urinary bladder and urethra
Answer: b
Clarification: The correct labelling of the given diagram is as shown below:

The given diagram represents the human urinary system. The human urinary system is a complex excretory system which is responsible for the concentration of urine and elimination of urea from the body.

8. How many nephrons are present in each kidney?
a) One million
b) One billion
c) One trillion
d) Two million
Answer: a
Clarification: Each kidney has approximately one million complex tubular structures called nephrons. These nephrons are the structural and functional units of the kidneys.

9. In how many parts a nephron is divided?
a) One
b) Two
c) Three
d) Four
Answer: b
Clarification: Each nephron is divided into two parts- the glomerulus and the renal tubule. The glomerulus is a tuft of capillaries while the renal tubule begins with a double-walled cup-like structure called Bowman’s capsule.

10. What will happen if the diameter of the afferent arteriole is less than efferent arteriole?
a) Dilute urine
b) Concentrated urine
c) No ultrafiltration
d) Black urine
Answer: c
Clarification: The afferent arteriole is a fine branch of the renal artery which has ha wider lumen than the efferent arteriole which carries blood away from the glomerulus. If the afferent arteriole diameter is less than the efferent arteriole, then ultrafiltration is not possible.

11. What does the question mark represents in the given figure?

a) Cortex
b) Medulla
c) Medullary pyramid
d) Renal pelvis
Answer: c
Clarification: The correct labelling of the given figure is as shown:

This figure represents the longitudinal section or a diagrammatic view of a kidney.

12. Starfishes are aminotelic organisms.
a) True
b) False
Answer: a
Clarification: Starfishes are aminotelic organisms as they excrete amino acids directly into the urine. Hippuric acid is an excretory waste formed by the combination of benzoic acid and glycine in mammals.

13. What are osmoregulators?
a) Animals which cannot change their body osmolarity
b) Animals which can change their osmolarity sometimes
c) Animals which can change their osmolarity
d) Animals which cannot excrete out waste
Answer: a
Clarification: Osmoregulators are the animals that cannot change their body osmolarity according to their external environment. They cannot tolerate a wide range of salinity.

14. Which of the following organism is not an osmoconformer?
a) Hagfish
b) Spongilla
c) Marine invertebrates
d) Skates
Answer: b
Clarification: Osmoconformers are the animals that can change their body osmolarity according to the external environment like hagfish, marine invertebrates, sharks, and skates.

15. Which of the following is not an adaptation of kangaroo rat?
a) Drinks water
b) Feeds on fatty seeds
c) Excretes concentrated urine
d) The nasal counter current system
Answer: a
Clarification: Kangaroo rat does not drink water as it feeds on fatty seeds because 1g of fat oxidation produces a double amount of water. It excretes out concentrated urine and has a nasal counter current system.

250+ TOP MCQs on Neural Coordination Basics and Answers

Biology Multiple Choice Questions on “Neural Coordination Basics”.

1. Which of the following integrates all the activities of the organs?
a) The neural and endocrine system
b) The neural and digestive system
c) Digestive and excretory system
d) Excretory and Respiratory system
Answer: a
Clarification: In our body, the neural and the endocrine system jointly coordinate and integrate all the activities of the organs so that they function in a synchronised fashion.

2. Which network does the neural system provide?
a) Cell to cell connection only
b) Point to point connection
c) Organ to organ connection only
d) Tissue to tissue connection only
Answer: a
Clarification: The neural system provides an organized network of point to point connections for quick coordination. These functions of the organs or the organ systems must be coordinated in our body to maintain homeostasis.

3. What is meant by coordination?
a) Only two organs interact
b) Only three organs interact
c) Only two organs systems interact
d) Two or more organs interact
Answer: d
Clarification: Coordination is the process through which two or more organs interact and complement the functions of one another. For example, the functions of muscles, lungs, heart, blood vessels, kidney, and other organs are coordinated while performing physical exercises.

4. What does the endocrine system provide us?
a) Chemical integration through cell secretions
b) Chemical integration through cell division
c) Chemical integration through hormones
d) Chemical integration through tissues
Answer: c
Clarification: The endocrine system provides chemical integration through the hormones. The neural and the endocrine systems jointly coordinate and regulate the physiological functions in the body.

5. Which of the following functions is not performed by neurons?
a) Detect the stimuli
b) Receive the stimuli
c) Transmit the stimuli
d) Secrete the stimuli
Answer: d
Clarification: The neurons are not responsible for secreting the stimuli. Instead, their main functions include-detecting, receiving and transmitting stimuli over large distances in our body.

6. What kind of neurons is present in Hydra?
a) Apolar neurons
b) Unipolar neurons
c) Bipolar neurons
d) Multipolar neurons
Answer: a
Clarification: The neural organisation is very simple in lower invertebrates. For example, Hydra neural organisation just consists of a network of neurons. Apolar or non-polar types of neurons are present in hydra.

7. The neural system of lower invertebrates is better than the insects.
a) True
b) False
Answer: b
Clarification: The neural system of insects is better organised than the lower invertebrates as a brain is present along with several ganglia and neural tissues. The vertebrates have a more developed neural system.

8. How can a nerve cell be distinguished from other cells of the body?
a) Presence of granules in nucleus
b) Presence of different nucleus
c) Presence of neurites
d) Presence of ribosomes
Answer: c
Clarification: A nerve cell can be distinguished from other cells of the body by the presence of neurites. Neurites are any projection from the cell body of the neuron-like dendrites or the axons.

9. What is the full form of PNS?
a) Peripheral neural systole
b) Peripheral nervous system
c) Peritubular neural systole
d) Peritubular nervous system
Answer: b
Clarification: PNS stands for the Peripheral nervous system. The PNS comprises of all the nerves of the body associated with the central nervous system-brain and the spinal cord.

10. How many different types of PNS fibres are there?
a) One
b) Two
c) Three
d) Four
Answer: b
Clarification: The nerve fibres of the PNS are of two types:
i. Afferent fibres which transmit impulses from tissues/organs to CNS
ii. Efferent fibres which transmit regulatory impulses from CNS to the concerned tissues/organs.

11. The peripheral nervous system has how many divisions?
a) Two
b) Three
c) Four
d) Five
Answer: a
Clarification: The PNS is divided into two major divisions called somatic neural system and autonomic neural system. The somatic neural system relays impulses from CNS to the skeletal muscles while ANS transmits impulses from CNS to the smooth muscles.

12. The visceral nervous system is the part of the peripheral nervous system.
a) True
b) False
Answer: a
Clarification: Visceral nervous system is the part of the peripheral nervous system that comprises the whole complex of nerves, fibres, ganglia, and plexuses by which impulses travel from the CNS to the viscera and vice-versa.

13. Which of the following is not a part of a neuron?
a) Cell body
b) Lignin
c) Dendrites
d) Axon
Answer: b
Clarification: A neuron is a microscopic structure composed of three major parts, namely, call body, dendrites, and axon. The cell body contains cytoplasm with typical cell organelles and certain granular bodies called Nissl’s granules.

14. What are the short repeatedly branched fibres called?
a) Axon
b) Cell body
c) Neurite
d) Dendrite
Answer: d
Clarification: Short and repeatedly branched fibres are called dendrites. These branches project out of the cell body of the neuron. These branches also contain Nissl’s granules in their cytoplasm.

15. What does each branch of axon terminate into?
a) Synaptic knob
b) Vesicles
c) Tubules
d) Another cell
Answer: a
Clarification: Each branch of an axon terminates into a synaptic knob. The axon is a long fibre which is branched at the end. Each branch terminates as a bulb-like structure called a synaptic knob. These knobs consist of some synaptic vesicles which contain some neurotransmitters like acetylcholine.

250+ TOP MCQs on Chemical Control and Coordination – Mechanism of Hormone Action and Answers

Biology Multiple Choice Questions on “Chemical Control and Coordination – Mechanism of Hormone Action”.

1. Hormone receptors are ______
a) glycolipids
b) lipids
c) polysaccharides
d) proteins
Answer: d
Clarification: Hormone receptors are proteinaceous in nature. These receptors are located on or inside the cells. It is where a hormone binds on a cell. The binding of the hormone signals the cells to perform their tasks.

2. Which of these is false regarding receptors?
a) Intracellular receptors are present within the cell
b) Receptors form complexes with hormones
c) Receptors disintegrate after contact with hormones
d) Receptors are specific
Answer: c
Clarification: Receptors are the structures of the cell to which hormones bind and form hormone-receptor complex. They do not disintegrate. Receptors are specific for each hormone. Intracellular receptors are present in the cytoplasm.

3. What type of hormone is glucagon?
a) Iodothyronines
b) Steroids
c) Peptide
d) Amino acid derivatives
Answer: c
Clarification: Glucagon is a peptide hormone. It is synthesized and secreted by the alpha cells of the pancreas. The function of glucagon is to break glycogen into glucose. This raises the blood sugar level.

4. Hypothalamic hormones are ______
a) peptides
b) steroids
c) iodothyronines
d) amino acid derivates
Answer: a
Clarification: Hypothalamic hormones are peptides. They are secreted by the hypothalamus. Peptides, steroids, iodothyronines and amino acid derivatives are the different categories of hormones.

5. Adrenaline is derived from ______
a) lipopolysaccharides
b) amino acids
c) lipids
d) sugars
Answer: b
Clarification: Adrenaline or epinephrine is derived from amino acids. It is secreted by the outer cortex of the pair of adrenal glands. It is the emergency hormone secreted during a fight or flight response.

6. Which of these is a secondary messenger?
a) Ca2+
b) Mg2+
c) Na+
d) K+
Answer: c
Clarification: Ca2+ is an important secondary messenger. It carries signals or messages from membrane receptors to the designated areas inside the cells. It is also important for muscle contractions.

7. IP3 is a(n) _____
a) secondary messenger
b) membrane receptor
c) intracellular receptor
d) nuclear receptor
Answer: a
Clarification: IP3 is an important secondary messenger. When a hormone binds to a receptor, it forms a hormone receptor complex. This hormone receptor complex transmits a secondary signal inside the cell via secondary messengers.

8. Which of these functions is not regulated by intracellular hormone-receptor complexes?
a) Regulation of gene expression
b) Regulation of chromosome function
c) Interaction with the genome
d) Regulation of K+ entry into the cell
Answer: d
Clarification: Intracellular hormone-receptor complexes transmit signals mainly to the nucleus for the regulation of gene expression, regulation of chromosome function through indirect interaction with the genome.

9. Identify the structure ‘x’.

a) Nuclear receptor
b) Intracellular receptor
c) Hormone-receptor complex
d) Gap junction
Answer: c
Clarification: When a hormone binds to a receptor it forms a hormone-receptor complex. The given hormone-receptor complex lies on the cell membrane. Hence, the hormone is bound to a membrane receptor.

10. The receptor for estrogen is intracellular. True or false?
a) True
b) False
Answer: a
Clarification: Estrogen is a steroid hormone secreted by the ovaries. Since it is a steroid hormone, estrogen can easily pass through the lipid bilayer of the cell membrane without a receptor. Thus its receptor lies in the cytoplasm, or the receptor is intracellular.