Tag: biology

Questions Related to biology

Flowering in Pineapple is promoted by

biology chemical coordination in plants ethylene plant hormones plants and animal hormones

  1. GA

  2. IAA

  3. Ethylene

  4. Both B and C

Show answer
Correct Option: D
Explanation:

Flowering in pineapple is not only based on external factors like temperature, daylength but also is based on internal factors like phytohormones. Pineapple flowering can be artificially induced by activity of the ethylene and IAA (indoleacetic acid). During flowering of pineapple, low temperature stimulates ethylene biosynthesis. Other hormones which are involved in initiating pineapple flowering are a-naphthalene acetic acid (NAA), indolbutiric acid (IBA), 2,4-dichlorofenoxiacetic acid (2,4-D). 

Thus, the correct answer is option D.

Ethylene is connected with

biology chemical coordination in plants ethylene plant hormones plants and animal hormones

  1. Aerobic respiration

  2. Climacteric respiration

  3. Anaerobic respiration

  4. Fermentation

Show answer
Correct Option: B
Explanation:

Ethylene is a plant hormone. It is also called as ripening hormone as it is responsible for ripening of fruits. Fruit ripening is accompanied by increase rate of respiration. The climacteric respiration occurs during fruit ripening which is associated with increased ethylene production. Due to increased respiration, complex carbohydrates are broken down into simpler sugars and cell wall becomes soft. 

Thus, the correct answer is option B.

Ethylene is metabolic product of

biology chemical coordination in plants ethylene plant hormones plants and animal hormones

  1. Valine

  2. Serine

  3. Methionine

  4. Glutamic acid

Show answer
Correct Option: C
Explanation:

Ethylene is a metabolic product of methionine. It is synthesized from methionine amino acid by methionine cycle or yang cycle. Methionine is first converted to adenosylmethionine. It is then converted to Aminocyclopropane carboxylic acid. It is then oxidized to form ethylene. It is a gaseous plant hormone which stimulates ripening of fruits in plants.

Thus, the correct answer is option C.

State whether the following statements are true or false.
Ethylene evolution is highest when the fruit is unripe but diminishes as the fruit matures.

biology chemical coordination in plants ethylene plant hormones plants and animal hormones

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

Ethylene is a gaseous hormone that promotes transverse growth but inhibits lateral growth. They are produced by the amino acid methionine. It was found that ripened fruits produce this hormone, so when the ripened fruits are placed together with unripe fruits, the unripe fruits will get ripened due to the release of this gas. Ethylene evolution is highest at the time of ripening but it diminishes when the fruit matures and the evolution of gas got reduced.

So, the correct statement is 'True'.

Choose the correct answer from the alternatives given.
Which of the following plant hormones stimulates the ripening of fruit and inhibits plant growth?

biology chemical coordination in plants ethylene plant hormones plants and animal hormones

  1. Abscisic acid

  2. Cytokinin

  3. Ethylene

  4. Gibberellin

Show answer
Correct Option: C
Explanation:
  • Ethylene is a simple gaseous PGR. 
  • It is synthesised in large amounts by tissues undergoing senescence and ripening fruits. 
  • Influences of ethylene on plants include horizontal growth of seedlings, swelling of the axis and apical hook formation in dicot seedlings. 
  • Ethylene promotes senescence and abscission of plant organs, especially of leaves and flowers. 
  • Ethylene is highly effective in fruit ripening
  • So, the correct option is 'Ethylene'.

Digestion of protein takes place in

parts of the digestive system digestive system of human human digestive system digestion and absorption biology nutrition deficiency diseases digestive system

  1. Duodenum and stomach

  2. Stomach and oesophagus

  3. Small and large intestine

  4. Intestine and rectum

Show answer
Correct Option: A

Which of the following is incorrect regarding the given digestion and absorption of protein?

parts of the digestive system digestive system of human human digestive system digestion and absorption biology nutrition deficiency diseases digestive system

  1. The breakdown of proteins to peptides is catalyzed by pepsin in the stomach and by the pancreatic enzymes trypsin and chymotrypsin in the small intestine.

  2. Peptides are broken down into amino acids by pancreatic carboxypeptidase and intestinal aminopeptidase.

  3. Small peptides consisting of two or three amino acids can diffuse through the epithelial cell and broken down into carbon dioxide and ammonia which are released into the blood.

  4. None of these

Show answer
Correct Option: B
Explanation:

  • Digestion of protein is initiated in the stomach by the enzyme pepsin.
  • In the small intestine, further digestion is done by trypsin, chymotrypsin, and carboxypeptidase into dipeptidase that releases from the pancreas.
  • Dipeptidase are broken into amino acids by intestinal dipeptidase.
  • These amino acids are absorbed actively by walls of intestine and release in the bloodstream.
  • These are utilized by tissues and broken down into carbon dioxide and ammonia.
  • Proteins require maximum energy to digest.

So the correct option is 'Peptides are broken down into amino acids by pancreatic carboxypeptidase and intestinal aminopeptidase.'

How does pepsinogen change into its active form?

parts of the digestive system digestive system of human human digestive system digestion and absorption biology nutrition deficiency diseases digestive system

  1. In the presence of hydrochloric acid

  2. In the presence of trypsin

  3. In the presence of  bile

  4. In the presence of carboxypeptidae

Show answer
Correct Option: A
Explanation:

 Parietal cells of stomach secrets hydrochloric acid which convert inactive pepsinogen to partially active pepsinogen, partially activates pepsinogen then cleaves the peptide from other pepsinogen molecules to form active pepsin which converts protein into proteases and peptides.

So, the correct answer is 'In the presence of hydrochloric acid'.

Which of the following is the correct matching of the site of action on the given substrate, the enzyme acting upon it and the end product?
(i) Small intestine: Protein $\xrightarrow{Pepsin}$ Amino acid
(ii) Stomach : Fat $\xrightarrow{Lipase}$ Micelles
(iii) Duodenum : Triglycerides $\xrightarrow{Trypsin}$ Monoglyceride 
(iv) Buccal cavity : Starch $\xrightarrow{Amylase}$ Disaccharide
(v) Jejunum: Peptones $\xrightarrow{Pepsin}$ Amino acid
(vi) Buccal cavity : Starch $\xrightarrow{Amyloglycerate}$ Maltose

parts of the digestive system digestive system of human human digestive system digestion and absorption biology nutrition deficiency diseases digestive system

  1. (i),(ii) and (iii) are correct

  2. (iv) only 

  3. (iv) and (v) are correct

  4. All are correct

Show answer
Correct Option: B
Explanation:

(i) Pepsin digest protein in the stomach.

(ii)Lipase digest emulsified fat in the intestine.
(iii)In duodenum trypsin digest protein or dipeptides.
(iv) Starch is digested into maltose by salivary amylase in the buccal cavity.
(v)Pepsin digest protein in the stomach.
(vi) Starch is digested into maltose by salivary amylase in the buccal cavity.
So the correct option is '(iv) only '

Read the given statements and select the option that correctly identifies them as true or false
1) Insulin has no effect on absorption of glucose from gastrointestinal tract
2) Fat absorption is greatest in the upper part of the small intestine
3) most vitamins are absorbed in the ileum

parts of the digestive system digestive system of human human digestive system digestion and absorption biology nutrition deficiency diseases digestive system

  1. True

  2. False

Show answer
Correct Option: A
Explanation:
1) Insulin has no effect on the absorption of glucose from the gastrointestinal tract as it increases the amount of glucose absorption when its concentration increase in blood.
2) Fat absorption is greatest in the upper part of the small intestine because in duodenum bile emulsifies it and form micelles which are absorbed form.
3) Most vitamins are absorbed in the ileum.
So the correct option is 'True'.