Osmoregulation MCQs and Note

Question 1

What is the objective of the study on plant excretion?

Answer 1

To learn how to describe the processes by which plants excrete substances and outline how some waste products may be used by the plant.

Question 2

Define Metabolism.

Answer 2

Metabolism describes all the chemical reactions that occur within living organisms to maintain life.

Question 3

What are metabolic processes in plants primarily responsible for?

Answer 3

Food synthesis through photosynthesis and energy release through cellular respiration.

Question 4

What is Metabolic Waste?

Answer 4

Products of metabolic reactions that are unnecessary or harmful to the organism and must be eliminated through excretion.

Question 5

Define Excretion.

Answer 5

Excretion is the removal of the waste products of metabolism from the body of an organism.

Question 6

Do plants have a specialized organ system for excretion?

Answer 6

No, plants do not have a specialized organ system for excretion.

Question 7

What is photosynthesis?

Answer 7

The process by which plants synthesize their own food in the form of glucose using carbon dioxide, water, and light energy.

Question 8

What is aerobic respiration?

Answer 8

The process by which energy is released in the cells in the presence of oxygen.

Question 9

Write the word equation for photosynthesis.

Answer 9

Carbon dioxide + water + light energy = glucose + oxygen + water.

Question 10

Write the word equation for respiration.

Answer 10

Glucose + oxygen = carbon dioxide + water + energy.

Question 11

What is the main gaseous waste product of photosynthesis?

Answer 11

Oxygen.

Question 12

What is the main gaseous waste product of respiration?

Answer 12

Carbon dioxide and water vapor.

Question 13

Define Stomata.

Answer 13

Stomata (singular: stoma) are pores in the epidermis of leaves through which gas exchange takes place with the atmosphere.

Question 14

What are Lenticels?

Answer 14

Lenticels are openings on the surfaces of stems and roots through which gas exchange takes place with the atmosphere.

Question 15

Define Transpiration.

Answer 15

Transpiration is the loss of water through evaporation from the aerial parts of a plant to the atmosphere.

Question 16

What percentage of water loss in plants is accounted for by stomatal transpiration?

Answer 16

About 90%.

Question 17

What percentage of water loss in plants is accounted for by lenticular transpiration?

Answer 17

About 0.1%.

Question 18

What is Cuticular transpiration?

Answer 18

The evaporation of water molecules through the cuticle, a waxy layer that coats the epidermis of the aerial parts of a plant.

Question 19

What is Guttation?

Answer 19

The process of excreting xylem sap through the hydathodes at the margins of leaves.

Question 20

What are Hydathodes?

Answer 20

Hydathodes are pores in the epidermis of leaf margins through which xylem sap is excreted during guttation.

Question 21

What is the primary substance excreted from the plant via guttation?

Answer 21

Xylem sap.

Question 22

What is root pressure?

Answer 22

The upward pressure created in the xylem vessels due to the absorption of water from the soil into the roots.

Question 23

How do plants manage nitrogenous waste?

Answer 23

They can excrete nitrogenous waste products like urea or reuse them for protein synthesis.

Question 24

What form can mineral salts take when they accumulate in plants?

Answer 24

They can be converted into insoluble crystals stored in the cytoplasm or vacuole.

Question 25

What is a cuticle?

Answer 25

A waxy layer that coats the epidermis of the aerial parts of a plant.

Question 26

What is one form of waste removal in plants?

Answer 26

Waste products can be stored in the leaves of a plant, which can then drop off when no longer required.

Question 27

What do plants accumulate in their roots, leaves, or tubers?

Answer 27

Insoluble crystals of calcium oxalate, called raphides ## Footnote Raphides serve as a form of waste storage for some plants.

Question 28

Where can waste products be stored in plants?

Answer 28

In the leaves ## Footnote Waste products stored in leaves drop off when no longer required.

Question 29

What are the key points about excretion in plants?

Answer 29

* Plants generate metabolic waste products * Gaseous waste products are used as substrates for opposite reactions * Gas exchange occurs to eliminate excess gaseous waste * Water is eliminated through transpiration * Guttation exudes water through hydathodes * Nitrogenous waste is reused in protein synthesis * Mineral salts may be stored as raphides

Question 30

What is the process of respiration in plants?

Answer 30

A chain of chemical reactions enabling energy synthesis ## Footnote Respiration involves inhalation of oxygen and exhalation of carbon dioxide.

Question 31

Do plants breathe?

Answer 31

Yes ## Footnote Plants require oxygen for respiration, similar to animals.

Question 32

What structures do plants use for gas exchange?

Answer 32

* Stomata (in leaves) * Lenticels (in stems) ## Footnote These structures facilitate gaseous exchange in plants.

Question 33

How does respiration differ from breathing in plants?

Answer 33

Breathing is a step in respiration ## Footnote Plants undergo respiration throughout their life, while breathing occurs differently.

Question 34

What is cellular respiration in plants?

Answer 34

The process of generating glucose molecules through photosynthesis ## Footnote Cellular respiration captures energy from sunlight and converts it into glucose.

Question 35

What occurs during respiration in roots?

Answer 35

Absorption of air from soil spaces ## Footnote Oxygen absorbed is used to liberate energy for transporting salts and minerals.

Question 36

What is the difference between respiration and photosynthesis?

Answer 36

* Photosynthesis synthesizes food * Respiration oxidizes food * Photosynthesis stores energy * Respiration releases energy * Photosynthesis is anabolic * Respiration is catabolic

Question 37

What are the two main types of respiration?

Answer 37

* Aerobic Respiration * Anaerobic Respiration

Question 38

Where does aerobic respiration take place?

Answer 38

In the mitochondria of eukaryotic entities ## Footnote This process requires atmospheric oxygen.

Question 39

What occurs during anaerobic respiration?

Answer 39

Incomplete oxidation of food, producing ethyl alcohol and carbon dioxide ## Footnote Anaerobic respiration occurs in the cytoplasm of prokaryotic entities.

Question 40

How do plants breathe?

Answer 40

Through cellular respiration ## Footnote Nutrients from soil are converted into energy.

Question 41

Do plants breathe at night?

Answer 41

Yes ## Footnote Plants respire throughout their life, both day and night.

Question 42

What is the respiratory organ in woody stems?

Answer 42

Lenticels ## Footnote Lenticels are small pores for gas exchange in woody plants.

Question 43

What role do stomata play in plant respiration?

Answer 43

Facilitate gaseous exchange ## Footnote Stomata open and close to regulate gas exchange.

Question 44

Which part of roots is involved in the exchange of respiratory gases?

Answer 44

Root hairs ## Footnote Root hairs are tubular extensions of the epidermis.

Question 45

Which factor decreases the water potential of a plant cell?

Answer 45

Increasing the solute concentration inside the cell ## Footnote Increasing solute concentration lowers water potential by reducing the free energy of water.

Question 46

What is the water potential of pure water?

Answer 46

Ψ = 0 by definition ## Footnote Pure water at atmospheric pressure has a water potential of zero.

Question 47

What happens to a plant cell in pure water?

Answer 47

Turgor pressure increases because water enters and expands the central vacuole ## Footnote Water enters the cell by osmosis, generating hydrostatic pressure against the cell wall.

Question 48

What primarily generates turgor pressure in plant cells?

Answer 48

Osmotic influx of water into the central vacuole ## Footnote The central vacuole accumulates solutes and draws in water osmotically.

Question 49

What occurs during plasmolysis in a plant cell?

Answer 49

The cytoplasm (protoplast) shrinks away from the cell wall as water is lost ## Footnote This happens in hypertonic environments causing loss of turgor.

Question 50

How does the central vacuole contribute to osmotic adjustment?

Answer 50

By sequestering excess solutes and ions to drive water uptake ## Footnote This lowers the vacuole’s osmotic potential, drawing water in under drought or saline conditions.

Question 51

What type of solutes do plants accumulate during water stress?

Answer 51

Small organic compounds like proline and glycine betaine ## Footnote These compatible solutes help lower osmotic potential without interfering with metabolism.

Question 52

What is a characteristic adaptation of halophytic plants?

Answer 52

Salt excretion glands that remove excess salt from tissues ## Footnote Halophytes have mechanisms to handle high soil salt concentrations.

Question 53

How do xerophytes conserve water?

Answer 53

By storing water in thick, fleshy tissues and having waxy or hairy leaves ## Footnote Xerophytes adapt to arid conditions with features like thick cuticles and reduced leaves.

Question 54

How do many bacteria respond to high external salt?

Answer 54

By synthesizing or importing compatible solutes (e.g., proline, glycine betaine) and accumulating K^+ ## Footnote This helps maintain cell turgor without toxic ion levels.

Question 55

What strategy do halophilic bacteria use to cope with hypersaline environments?

Answer 55

Accumulating inorganic ions (like K^+) and organic osmolytes inside the cytoplasm ## Footnote This is known as the 'salt-in' or compatible-solute strategy.

Question 56

Which molecule acts as a compatible solute in microbial osmoregulation?

Answer 56

Proline ## Footnote Compatible solutes are small, highly soluble organic molecules that protect cell metabolism.

Question 57

What hormone do plants synthesize under drought conditions to induce stomatal closure?

Answer 57

Abscisic acid (ABA) ## Footnote ABA triggers stomatal closure to conserve water during water-deficit stress.

Question 58

How do freshwater protists avoid lysis in dilute environments?

Answer 58

By using contractile vacuoles that expel excess water ## Footnote This osmoregulatory pump prevents bursting in hypotonic environments.

Question 59

What is a major difference between plant and microbial osmoregulation?

Answer 59

Plants utilize a central vacuole for osmotic adjustment, whereas bacteria often adjust their cytoplasm’s solute balance instead ## Footnote Plant cells sequester ions and osmolytes in a large central vacuole.