CBSE Questions for Class 10 Biology Life Processes Quiz 10 - MCQExams.com

• Saliva secreted by salivary glands doesn't give safety against dental caries.
  
• Dental carries take place due to deposition of food particles on teeth and subsequent bacterial decay.
  
• So, the correct option is 'Give safely against dental carries'.

• Desert plants have a special mechanism known as CAM metabolism (Crassulacean acid metabolism). 
• During day the stomata are closed to conserve water molecules. At nights, the Carbon dioxide is converted to an acid and stored. 
• This acid is then utilized by plants during photosynthesis at day time.

• Urine from nephrons is brought to the collecting duct of kidneys where the urine enters the ureters. 
• There are 2 ureters, each opening from one kidney into the urinary bladder. 
• The urinary bladder stores urine and its size increases as the amount of urine collected increases. 
• When the urinary bladder gets completely filled, CNS gives a voluntary message (felt like the urge to urinate), the muscles of the bladder contract and the bladder sphincter relax thus excreting urine out through the urethra.

• The normal pH range for saliva is 6.2 to 7.6.
• The pH levels of the blood are normally within the range of 7.35 to 7.45. 
• Human gastric juice is acidic, with a pH of around 1.8 
• The pH values of urine are usually between 6.0 and 7.5, making it slightly acidic.

• All the green plants are - producers, so they make their own food. 
• Animals don't make their own food. They are heterotrophs. 
• Carbon dioxide and water are required for the process of photosynthesis in plants.
• Oxygen liberates in the process of photosynthesis.
  Statement (I) and (iv) are the correct statements.

• The Plant vessels are made of special cells, forming the vascular tissue. These tissues are a group of cells that perform specialised  function in an organism.
• Xylem and phloem are the vascular tissues which transport substances in plants.
• Thus, Option A is correct.
  

$$\textbf{Correct answer: D}$$ 

$$\textbf{Option (A):}$$ 

$$\bullet$$ Enzymes for the digestion of all the nutrients are present in the small intestine.

$$\bullet$$ This is why complete digestion occurs in the small intestine.

$$\textbf{Option (B):}$$ 

$$\bullet$$ The presence of villi increases the surface area of the intestinal epithelium.

$$\bullet$$ This high surface area is suitable for the absorption of digested food.

$$\bullet$$ The villi present on the small intestine facilitate easy absorption of the digested nutrients. 

$$\textbf{Option (C):}$$ 

$$\bullet$$ The wall of the intestine is supplied with blood vessels so that the absorbed nutrients can be transported to the vessels and it further gets transported to the body cells. 

$$\textbf{Option (D):}$$ 

$$\bullet$$ All of the characters of the small intestine are responsible for the absorption of digested food in the small intestine.

Hence, the correct answer is option (D).