Chapter 13: Thermoregulation & Osmoregulation— MCQs Explanation
Homeostasis is best defined as:
Correct Answer: (b) Maintenance of a stable internal environment despite external changes
Explanation: Homeostasis ka matlab hai bahar ki tabdeeli (tul-mausem ya maahol) ke bawajood jism ke andaruni maahol (temperature, water, pH wagairah) ko aik khas limit mein baqaim rakhna.
Which term covers/encompasses the rest of the three?
Correct Answer: (d) Homeostasis
Explanation: Homeostasis aik main term hai jiske andar Osmoregulation (paani/namak ka tawazun), Excretion (fuzlaat ka nikas), aur Thermoregulation (hararat ka tawazun) teeno aate hain.
Which of the following is NOT one of the three basic elements of the homeostatic mechanism?
Correct Answer: (d) Enzymes
Explanation: Homeostatic system ke 3 bunyadi hissey hotay hain: Receptors (jo change detect karte hain), Control centre (jo decision leta hai), aur Effectors (jo action lete hain). Enzymes is basic mechanism ka hissa nahi hain.
Receptors are best described as structures that:
Correct Answer: (b) Detect changes in the internal or external environment
Explanation: Receptors special cells ya organs hotay hain jo jism ke andar ya bahar hone wali kisi bhi tabdeeli (stimulus) ko mehsoos/detect karte hain.
Which of the following act as control centres in homeostasis?
Correct Answer: (b) Brain, spinal cord and endocrine glands
Explanation: Brain, spinal cord, aur glands control centre ka kaam karte hain kyunke ye receptors se message receive karke faisla karte hain ke jism ko kya response dena chahiye.
Effectors respond to a message from the control centre by:
Correct Answer: (b) Contracting (muscles) or secreting (glands)
Explanation: Effectors (jaise muscles aur glands) control centre ka paigham milne par ya to contract hote hain (muscles) ya phir chemical/hormone secrete karte hain (glands).
Feedback mechanisms are the foundation of:
Correct Answer: (b) Homeostasis
Explanation: Homeostasis feedback mechanisms par chalta hai, kyunke feedback se hi jism ko pata chalta hai ke kisi process ko kam karna hai ya barhana hai.
Which type of feedback reduces the activity of a system and is the most common form of regulation?
Correct Answer: (b) Negative feedback
Explanation: Negative feedback system ki activity ko kam karke normal level par laata hai (jaise bukhar kam karna). Ye sab se common mechanism hai.
Which of the following is an example of positive feedback?
Correct Answer: (c) Release of oxytocin during childbirth
Explanation: Positive feedback reaction ko aur barhata hai. Childbirth ke dauran oxytocin release hone se contractions barhti hain, jisse aur oxytocin nikalta hai.
In the negative feedback system for body temperature, which structure acts as the control centre?
Correct Answer: (c) Thermoregulator (hypothalamus)
Explanation: Brain ka hissa Hypothalamus jism ke temperature ko control karne wala main thermostat/control centre hota hai.
Unregulated positive feedback in severe infection/inflammation is caused by excessive release of:
Correct Answer: (b) Cytokines
Explanation: Shdeed infection mein immune system zaroorat se zyada Cytokines release karta hai (Cytokine storm), jo positive feedback ko out of control kar deta hai.
During childbirth, the control centre sends signals to which gland to release oxytocin?
Correct Answer: (b) Pituitary gland
Explanation: Childbirth ke waqt brain (hypothalamus) Pituitary gland ko signal bhejta hai taa ke wo Oxytocin hormone release kare.
13.2 Osmoregulation
Osmoregulation is the maintenance of the balance of:
Correct Answer: (b) Water and solutes in body fluids
Explanation: Osmoregulation jism ke fluids mein paani (water) aur namkiyaat (solutes) ki miqdar ko tawazun mein rakhne ka naam hai.
Animals which allow their body fluid concentration to match their environment are called:
Correct Answer: (b) Osmoconformers
Explanation: Osmoconformers wo janwar hote hain jo apne jism ke paani aur namak ki concentration ko bahar ke maahol ke barabar (isotonic) rakhte hain.
Which of the following is an example of an osmoconformer?
Correct Answer: (b) Marine sharks and rays
Explanation: Samundari sharks aur rays apne jism mein urea/TMAO retain karke samundari paani ke sath osmoconform karti hain.
Freshwater animals are generally ______ to their environment.
Correct Answer: (c) Hypertonic
Explanation: Freshwater animals ke andar namkiyaat zyada hoti hain aur bahar ke paani mein kam, is liye unka jism external environment ke muqable mein Hypertonic hota hai.
How do freshwater fish primarily gain water?
Correct Answer: (c) Osmosis
Explanation: Freshwater fish hypertonic hoti hain, is liye unki body/gills ke zariye bahar se paani qudrati tor par Osmosis ke zariye andar dakhil hota rehta hai.
Marine fishes compensate for water loss by:
Correct Answer: (b) Drinking seawater
Explanation: Samundari machliyan hypotonic hoti hain aur unka paani bahar nikalta rehta hai, is kami ko pura karne ke liye wo samundari paani peeti hain.
Chloride cells in the gills of marine fishes function to:
Correct Answer: (b) Actively pump excess salts out of the blood
Explanation: Samundari paani peene se jo zyaada namak jism mein jaata hai, Chloride cells us zazaid salt ko active transport ke zariye gills se bahar nikaalte hain.
Rectal glands found in some marine fishes help to:
Correct Answer: (b) Remove excess salts from blood into the digestive tract
Explanation: Sharks aur kuch marine fishes mein Rectal glands hote hain jo khoon se extra salt ko nikaal kar digestive tract (rectum) mein phenkte hain.
Terrestrial insects prevent evaporative water loss with the help of:
Correct Answer: (b) A waxy exoskeleton made of chitin
Explanation: Khushki par rehne wale keeron (insects) ke upar Chitin ki bani waxy layer hoti hai jo paani ko bhaap ban kar urne se rokti hai.
Tardigrades (water bears) surviving in a dormant, water-deprived state is known as:
Correct Answer: (b) Anhydrobiosis
Explanation: Jab paani bilkul khatam ho jaye to Tardigrades bilkul khushk ho kar aik dormant/soyi hui halat mein chale jaate hain, is abillity ko Anhydrobiosis kehte hain.
To conserve water, terrestrial animals convert ammonia into:
Correct Answer: (b) Urea or uric acid
Explanation: Ammonia bohot toxic hoti hai aur usse nikalne ke liye bohot paani chahiye hota hai, is liye zameeni janwar usay kam toxic Urea ya Uric acid mein badal dete hain taa ke paani bachat ho sakay.
Which nitrogenous waste requires the LEAST amount of water for excretion?
Correct Answer: (c) Uric acid
Explanation: Uric acid ko khareej karne ke liye sab se kam (ya na hone ke barabar) paani ki zaroorat hoti hai (paste/crystal form mein khareej hota hai).
Which waste product requires the most water for excretion?
Correct Answer: (a) Ammonia
Explanation: Ammonia highly toxic hoti hai, is liye 1 gram Ammonia ko nikaalne ke liye taqreeban 500ml paani ki zaroorat hoti hai (sab se zyada paani).
Animals which excrete ammonia as their major nitrogenous waste are called:
Correct Answer: (c) Ammonotelic
Explanation: Wo janwar jo apna mukhy nitrogenous waste Ammonia ki shakal mein khareej karte hain unhein Ammonotelic kehte hain (jaise aquatic animals).
In which part of the body does the conversion of ammonia to urea take place?
Correct Answer: (a) Liver
Explanation: Ammonia ko Urea mein convert karne ka kaam (Urea cycle) jigar yani Liver mein hota hai.
Excess uric acid in the blood can lead to a painful condition known as:
Correct Answer: (b) Gout
Explanation: Jab khoon mein Uric acid barh jata hai to uske crystals jodron (joints) mein jama ho jaate hain jisse shdeed dard hota hai, is bimari ko Gout kehte hain.
13.3 Thermoregulation
Thermoregulation is the homeostatic process of maintaining:
Correct Answer: (b) Internal body temperature within a tolerable range
Explanation: Thermoregulation jism ke andaruni temperature ko aik munasib/bardasht ke kabil range mein barqaraar rakhne ke process ko kehte hain.
Animals that gain most of their body heat from external sources are called:
Correct Answer: (b) Ectotherms
Explanation: Ectotherms wo janwar hote hain jo apne jism ki garmi bahar ke maahol (sooraj, garam chattano) se hasil karte hain.
Which of the following are examples of endotherms?
Correct Answer: (c) Birds and mammals
Explanation: Birds aur Mammals endotherms hain kyunke ye apne andaruni metabolism se apni body heat paida karte hain.
What is the primary heat source for endotherms?
Correct Answer: (b) Internal metabolism
Explanation: Endotherms ki heat ka main zariya unka apna internal metabolism (chemical reactions) hota hai.
Animals unable to maintain their body temperature within narrow limits are called:
Correct Answer: (b) Poikilotherms
Explanation: Poikilotherms wo janwar hain jinka body temperature bahar ke maahol ke sath badalta rehta hai aur constant nahi rehta.
Being a poikilotherm helps an animal survive in a nutrient-poor environment because:
Correct Answer: (b) It doesn’t need massive food to fuel a constant temperature
Explanation: Kyunke Poikilotherms ko body temperature maintain rakhne ke liye internal heat paida nahi karni parti, is liye unhein kam khana chahiye hota hai.
What is the control centre for human thermoregulation?
Correct Answer: (b) Hypothalamus
Explanation: Insani dimagh ka hissa Hypothalamus thermoregulation ka main control centre hai.
During hyperthermia, which response helps cool the body by expanding blood capillaries?
Correct Answer: (b) Vasodilation
Explanation: Hyperthermia (garmi barhna) mein khoon ki naaliyan phool jati hain (Vasodilation), jisse ziada khoon jild ke qareeb aata hai aur garmi bahar nikal jati hai.
Evaporation of sweat from the skin surface helps to:
Correct Answer: (b) Produce a cooling effect
Explanation: Jab paseena (sweat) jild se bhaap ban kar urta hai (evaporation), to wo apne sath garmi le jata hai jisse cooling effect paida hota hai.
During hyperthermia, the thyroid gland may decrease secretion of:
Correct Answer: (b) Thyroxine
Explanation: Thyroxine hormone metabolic rate aur heat paida karta hai. Garmi mein body heat kam karne ke liye Thyroid gland Thyroxine ki secretion kam kar deta hai.
Which of the following is a response to hypothermia (cooling)?
Correct Answer: (c) Shivering
Explanation: Hypothermia (sardi lagna) ke dauran jism kaanpna (Shivering) shuru kar deta hai taa ke muscle movement se heat paida ho sakay.
Goosebumps are caused by the contraction of tiny muscles at the base of:
Correct Answer: (b) Hair follicles
Explanation: Sardi mein hair follicles ke saath juray chote muscles contract hote hain jisse baal khade ho jaate hain (Goosebumps) taa ke hawa ki insulating layer ban sakay.
An ectotherm basking in the sun gains heat mainly by:
Correct Answer: (b) Radiation
Explanation: Sooraj ki kirno se garmi hasil karna Radiation ke zariye hota hai.
An ectotherm sitting on a warm rock gains heat mainly by:
Correct Answer: (b) Conduction
Explanation: Jab koi janwar kisi garam cheez (jaise garam chattan) ke sath direct touch mein ho kar garmi le, to usay Conduction kehte hain.