• 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'.

(A)Photosynthesis is a physiochemical process where fatty acids are converted to sugar.

The figure is a photosynthesis process where the leaf of a plant takes out carbon dioxide and gives out oxygen.

The instrument used to measure blood pressure is known as a sphygmomanometer. The normal blood pressure of a healthy person is 120/80 mm Hg, where 120 is the systolic pressure limit. Diastolic pressure shows the rate of heart relaxation. It is the pressure generated by blood flow as a result of relaxation of the heart. 

Solution:

The diastolic pressure is the pressure in the arteries when the heart rests between beats.

The collecting duct, glomerulus and Bowman's capsule are a part of nephrons. Nephrons are the basic unit of the excretory system in humans, but the alveoli are part of the respiratory system.

• 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.

The correct answer is B (Amphibians and reptiles )

Aerobic respiration is a process which takes place in the presence of oxygen to break down food into pyruvate and then into carbon dioxide and water, and energy is released.

Aerobic respiration takes place in the presence of oxygen.

During the photosynthesis process,  water is split into oxygen molecules and carbon is reduced into carbohydrates molecules. On the other hand, respiration is an energy-releasing enzymatic controlled catabolic process that includes an oxidative breakdown of food material inside a living cell.

• 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.

A. Animals

 

• 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.

Hence, from out of the given options the human blood has the highest pH.

Nitrogenous wastes, salts and excess water are removed from blood in the kidney and not in the liver. The process of removal of these nitrogenous waste, salts and water is called excretion.

'Hydrochloric acid' is an acid that is secreted in the stomach. It helps to kill the harmful bacteria that may enter the food. 

 Photosynthesis is the process done by leaves, for which sunlight, carbon dioxide, chlorophyll and water are necessary. The primary product is glucose and oxygen is released as a byproduct.

True: All heterotrophs have a basic process of nutrition similar. They break down the glucose formed by the autotrophs and get the energy out of nutrients by the process of respiration.

An organism that prepares food for itself using Carbon dioxide, water in the existence of 'sunlight' and 'chlorophyll' is referred to as 'autotrophs'. 

The saliva contains amylase enzyme that breaks down starch into simple sugar. 

• 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.

A. Heterotrophs do not synthesise their own food.

Haemoglobin, an heme or iron containing protein present in the RBC imparts red color to the blood.

The blood pressure in healthy human is 120/80 mm Hg.

Blood is purified or Oxygenated in the lungs. The right ventricle pumps deoxygenated blood through the pulmonary arteries into the lung for oxygenation or purification.

6CO2 + 6H2O + energy --> C6H12O6+ 6O2;

The small intestine is longer than the large intestine. It is about 7 metres long while the large intestine is about 1.5 meters long. The large intestine is wider than the small intestine.

The statement is false. 

The by-products formed in the body have to be removed because neither they are of any use to the body, nor are harmless, thus waste by-products are needed to be removed from the body and discarded outside by a process called excretion.
The correct option is C.

Oxidising-reducing reactions help to break down complex molecules into simpler substances. The process of acquiring oxygen from outside the body, and to use it in the process of break-down of food sources for cellular needs, is what we call respiration.
The correct option is A.

• 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.
  

Bronchi are the main passageway into the lungs, formed from the trachea. They are hollow tubes surrounded by cartilage rings. They are lined with cilia and mucus-secreting cells. Mucus traps pathogens and prevents their entry into the lungs. 

Regulation includes all the processes within an organism that control and coordinate the many activities that a living organism must perform to adjust to the internal and external environment. Reproduction is the process by which organisms replicate themselves. Cellular respiration is the set of metabolic reactions and processes that take place in the cells of organisms to convert biochemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products. Excretion is the process by which waste products of metabolism and other non-useful materials are eliminated from an organism. 

$$\textbf{Correct answer: D}$$ 

$$\textbf{Option (A):}$$ 

$$\bullet$$ 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).

The stomach starts chemical digestion of protein. The enzyme pepsin is responsible for protein breakdown. The large intestine is primarily responsible for removing water from the contents of the intestine and making it ready for removal from the body. The small intestine is the part of the intestines where 90% of the digestion and absorption of food occurs. The main function of the small intestine is absorption of nutrients and minerals from food. Liver is an accessory digestive gland and produces bile, an alkaline compound which aids in digestion via the emulsification of lipids. 

Platelets are the colourless cell fragments present in the blood. They are involved in the clotting. In the absence of platelets, the process of clotting will be affected. If there will be any wound when platelets are absent, the animal will die by shredding of all the blood.