Life Sciences Questions and Answers – Digestive & Excretory System

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This set of Life Sciences Multiple Choice Questions & Answers (MCQs) focuses on “Digestive & Excretory System”.

1. What is the pH of the saliva?
a) 3-5
b) 7-8
c) 5.5-6.2
d) 6.2-7.4
View Answer

Answer: d
Explanation: Saliva is a colorless viscous liquid which has a pH between 6.2 to 7.4. The enzyme present in saliva shows its optimal activity at pH 6.8.
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2. Digestion of food begins in the mouth itself.
a) True
b) False
View Answer

Answer: a
Explanation: Saliva contains amylase enzyme which digests the carbohydrate present in the food. It breaks down polysaccharides onto maltose, which is a disaccharide.

3. Out of the following, which is a major secretory layer of the GI tract?
a) Mucosa
b) Submucosa
c) Muscularis
d) Serosa
View Answer

Answer: a
Explanation: GI tract or Gastrointestinal tract is composed of four layers, i.e., mucosa, submucosa, muscularis, and serosa. Mucosa lines the lumen of the GI tract and is the major absorptive and secretory layer.
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4. Which of the following is NOT the salivary protein?
a) Lysozyme
b) Mucus
c) Phosphatase
d) Amylase
View Answer

Answer: c
Explanation: Salivary proteins are those which are present in the saliva. It includes amylase, lysozyme, and mucus.

5. Name the type of secretory cell which secretes hydrochloric acid in the stomach?
a) D-cell
b) G-cell
c) Mucous cell
d) Parietal cell
View Answer

Answer: d
Explanation: Hydrochloric acid or gastric juice in the stomach is secreted by parietal cells while G-cell secretes gastrin and D-cells secrete somatostatin.
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6. Which of the following is NOT the function of the large intestine?
a) Forming feces
b) Absorb 90% of nutrients
c) Defecating
d) Absorbing some water, ions, and vitamins
View Answer

Answer: b
Explanation: Large intestine does not absorb nutrients, but it absorbs some amount of water along with ions and vitamins. About 90% of nutrients are absorbed by the small intestine.

7. Which of the following gastric secretion phase prepares mouth and stomach for food?
a) Intestinal phase
b) Gastric phase
c) Cephalic phase
d) Early phase
View Answer

Answer: c
Explanation: Gastric secretion has been divided into three phases, i.e., gastric phase, cephalic phase, and intestinal phase. Cephalic phase refers to the increased secretion of HCl and pepsinogen, which prepares mouth and stomach for the food.
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8. Which of the following kidney function is NOT true?
a) Regulate blood volume and composition
b) Synthesize glucose
c) Regulate blood pressure
d) Defend the body against disease
View Answer

Answer: d
Explanation: Kidney is the primary organ of excretion, it removes the nitrogenous waste from the body and maintain homeostasis also. Kidneys also synthesize glucose and hormone, regulate blood pressure and maintain the volume and composition of blood.

9. Both kidneys are in the same position in the body.
a) True
b) False
View Answer

Answer: b
Explanation: Right side kidney is slightly lower than the left side kidney as in right side some space has been occupied by the liver.
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10. Out of the following, which is the first step in urine production?
a) Glomerular filtration
b) Tubular secretion
c) Tubular reabsorption
d) Urinary bladder store urine
View Answer

Answer: a
Explanation: Glomerular filtration is the first step in urine production where water and other solutes in the blood plasma moves across its wall and passes to renal tubule.

11. What is the daily volume of glomerular filtrate in adult male and female?
a) 50 liter in male and 90 liters in females
b) 120 liter in male and 130 liters in females
c) 180 liter in male and 150 liters in females
d) 180 liter in male and 180 liters in females
View Answer

Answer: c
Explanation: Average glomerular filtrate is 180 liter in male and 150 liters in female daily. More than 99% of the filtrate returns to the blood by tubular reabsorption and only 1-2 liter is excreted as urine.

12. Which of the following hormone plays a major role in water reabsorption?
a) Somatostatin
b) Relaxasin
c) Oxytocin
d) Vasopressin
View Answer

Answer: d
Explanation: Vasopressin is also known as antidiuretic hormone, released from the posterior lobe of the pituitary gland. ADH absorbs more water into the blood and decreases the amount of urine.

13. What is micturition?
a) Formation of feces
b) Discharge of urine
c) Defecating
d) Formation of sperm
View Answer

Answer: b
Explanation: Micturition is also known as urination or voiding. It’s the process of discharge of urine from the urinary bladder. When the volume of urine rises from 200-400 ml, pressure increases and causes micturition reflex.

14. Which of the following is NOT the characteristics of the normal urine?
a) Yellow or amber color
b) Mildly aromatic
c) 3-4 pH
d) 1.001 to 1.035 specific gravity
View Answer

Answer: c
Explanation: pH of urine varies from 4.6 to 8 or average 6 but it varies with the diet like more intake of protein makes the urine acidic or more vegetarian diet increases its alkalinity.

Sanfoundry Global Education & Learning Series – Life Sciences.

To practice all areas of Life Sciences, here is complete set of 1000+ Multiple Choice Questions and Answers.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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