Write major classes of Biomolecules.

Question:

Write major classes of Biomolecules.

Answer:

There are four major classes of Biomolecules –  Carbohydrates, Proteins, Nucleic acids and Lipids. Each of them is discussed below.

Carbohydrates

Carbohydrates are chemically defined as polyhydroxy aldehydes or ketones or compounds which produce them on hydrolysis. In layman’s terms, we acknowledge carbohydrates as sugars or substances that taste sweet. They are collectively called as saccharides (Greek: sakcharon = sugar). Depending on the number of constituting sugar units obtained upon hydrolysis, they are classified as monosaccharides (1 unit), oligosaccharides (2-10 units) and polysaccharides (more than 10 units). They have multiple functions’ viz. they’re the most abundant dietary source of energy; they are structurally very important for many living organisms as they form a major structural component, e.g. cellulose is an important structural fibre for plants.

Proteins

Proteins are another class of indispensable biomolecules, which make up around 50per cent of the cellular dry weight. Proteins are polymers of amino acids arranged in the form of polypeptide chains. The structure of proteins is classified as primary, secondary, tertiary and quaternary in some cases. These structures are based on the level of complexity of the folding of a polypeptide chain. Proteins play both structural and dynamic roles. Myosin is the protein that allows movement by contraction of muscles. Most enzymes are proteinaceous in nature.

Nucleic Acids

Nucleic acids refer to the genetic material found in the cell that carries all the hereditary information from parents to progeny. There are two types of nucleic acids namely, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). The main function of nucleic acid is the transfer of genetic information and synthesis of proteins by processes known as translation and transcription. The monomeric unit of nucleic acids is known as nucleotide and is composed of a nitrogenous base, pentose sugar, and phosphate. The nucleotides are linked by a 3’ and 5’ phosphodiester bond. The nitrogen base attached to the pentose sugar makes the nucleotide distinct. There are 4 major nitrogenous bases found in DNA: adenine, guanine, cytosine, and thymine. In RNA, thymine is replaced by uracil. The DNA structure is described as a double-helix or double-helical structure which is formed by hydrogen bonding between the bases of two antiparallel polynucleotide chains. Overall, the DNA structure looks similar to a twisted ladder.

Lipids

Lipids are organic substances that are insoluble in water, soluble in organic solvents, are related to fatty acids and are utilized by the living cell. They include fats, waxes, sterols, fat-soluble vitamins, mono-, di- or triglycerides, phospholipids, etc. Unlike carbohydrates, proteins, and nucleic acids, lipids are not polymeric molecules. Lipids play a great role in the cellular structure and are the chief source of energy.

Write Difference between Red Blood Cells and White Blood Cells.

Question:

Write Difference between Red Blood Cells and White Blood Cells.

Answer:

Difference between Red Blood Cells and White Blood Cells:

The significant differences between red blood cells and white blood cells are as follows:

RBC – Red Blood Cells	WBC – White Blood Cells
Red blood cells are called Erythrocytes.	White Blood Cells are called Leucocytes or Leukocytes.
RBCs have a bi-concave disc shape	WBCs have an irregular shape.
Size varies from 6 – 8 µm in diameter.	Size varies from 12 – 17 µm in diameter.
The lifespan of RBC is about 120 days.	The lifespan of WBC is around 12-20 days after which they are destroyed in the lymphatic system
Red blood cells do not have a nucleus on maturity.	WBCs are characterized by the presence of a large central nucleus.
Due to the presence of haemoglobin, these cells appear red in colour.	These cells are colourless, as they do not have any pigment.
Only one type of RBC exists.	Different types of WBCs are found in the blood such as neutrophils, B lymphocytes, T lymphocytes, monocytes, basophils, eosinophils.
They help in the transport of respiratory gases to different parts of the human body	They help in producing antibodies to fight against disease-causing microbes.
RBCs are produced in the red bone marrow	These cells are produced in the red bone marrow, lymph nodes, and spleen.
The components of red blood cells are haemoglobin.	The components of white blood cells are antibodies with the presence of MHC (major histocompatibility complex) antigen cell markers.
These cells make up around 36-50% of human blood.	They make up around 1% of the human blood.
RBC count: 5 million/ mm³ of blood.	WBC count: 7000–8000/mm³ of blood.
The process of formation of RBC is known as erythropoiesis.	The process of formation of WBC is known as leukopoiesis.
These cells move between the cardiovascular systems.	These cells move between the cardiovascular and lymphatic systems.
Low count of RBCs results in Anaemia.	Low count of WBCs results in Leukopenia.

Write Features and Significance of Meiosis.

Question:

Write Features and Significance of Meiosis.

Answer:

Features of Meiosis

• It results in the formation of four daughter cells in each cycle of cell division.
• The daughter cells are identical to the mother cell in shape and size but different in chromosome number.
• The daughter cells are haploid.
• Recombination and segregation take place in meiosis.
• The process occurs in the reproductive organs and results in the formation of gametes.
• The process is divided into two types-Meiosis-I reduces the chromosome number to half and is known as reductional division. Meiosis-II is just like the mitotic division.

Significance

1. Meiosis is responsible for the formation of sex cells or gametes that are responsible for sexual reproduction.
2. It activates the genetic information for the development of sex cells and deactivates the sporophytic information.
3. It maintains the constant number of chromosomes by halving the same. This is important because the chromosome number doubles after fertilization.
4. In this process independent assortment of maternal and paternal chromosomes takes place. Thus the chromosomes and the traits controlled by them are reshuffled.
5. The genetic mutation occurs due to irregularities in cell division by meiosis. The mutations that are beneficial are carried on by natural selection.
6. Crossing over produces a new combination of traits and variations.

 

Write Major Endocrine Glands.

Question:

Write Major Endocrine Glands.

Answer:

Major Endocrine Glands

Pituitary gland

Enclosed deep within the skull, the pituitary gland is the size of a pea. It hangs on a stalk at the base of the brain. It consists of an anterior portion that produces hormones and a posterior portion that has many neural links. This gland is regarded as the master gland as it controls the functions of all the other glands (such as the adrenal, thyroid glands) in the endocrine system. The pituitary gland stimulates the adrenal gland to secrete cortisol, a steroid hormone controls a range of activities from controlling the body’s metabolism to stimulating blood pressure. The pituitary gland also secretes prolactin, which stimulates the production of milk.

Thyroid gland

The thyroid glands can be found at the front of the neck. It sits low in the throat, between the windpipe. Brownish red, it has blood vessels coursing through it. It secretes hormones that are collectively called thyroid hormones. The most prominent are T3 and T4, which influence the body’s rate of metabolism.

Parathyroid glands

The parathyroid glands consist of four small glands that are located behind the thyroids in the neck. They influence the calcium levels in the body by producing a hormone called Parathyroid Hormone. Sometimes, when the gland produces excess parathyroid hormones, it can have negative effects such as brittle bones and kidney stones.

Adrenal glands

The adrenal glands sit atop the kidneys and are no larger than a walnut. These glands produce over 150 hormones that regulate different functions in the body. The most well known is Adrenaline, which triggers the flight or fight response. In other words, this is a stress hormone that helps the organism to either face a dangerous situation or to avoid it altogether. It does this by:

• Increasing blood sugar levels
• Increasing the blood supply to the muscles, particularly to the limbs.
• Dilating the pupils
• Increasing the heart rate
• Tightening the jaw muscles.

Pancreas

The pancreas is exocrine as well as an endocrine gland that sits behind the stomach. It is roughly 6 inches long and rather flat. The pancreas has two primary roles to play:

• Producing digestive enzymes
• Producing hormones such as insulin and glucagon.

Insulin is produced by the β cells in the pancreas and it helps in regulating the blood glucose levels in the body from getting too high. As we are all aware, the lack of insulin causes type 1 and type 2 diabetes. The hormone glucagon is produced by α cells of the pancreas and it helps the body to prevent the glucose levels from dropping too low. Lack of glucagon leads to hypoglycemia. Another key difference between the two is insulin becomes active when the blood glucose levels are high, and glucagon become active only when blood glucose levels are low.

Gonads

Some glands are specific to males or females. For instance, the ovaries are specific to females and are located in the pelvic cavity. While the testes are specific to males. Ovaries produce estrogen that is important for reproduction and female sex characteristics. Testes produce testosterone that is responsible for male sex characteristics. Also, it results in increased muscle mass and body hair.

Pineal gland

The pineal gland is located between the two halves of the brain. It was also known as the “third eye” for most of history due to its location in the brain and its connection with light.

It produces a hormone known as melatonin which influences the body’s internal clock. Also known as the Circadian Rhythm, it influences the body’s sleep/wake cycle. Its effects are not really noticeable unless the individual is sleep-deprived. Factors such as jet lag, or working the night shift has a more noticeable effect on an individual because Circadian rhythm tends to coincide with the day and night cycle. That’s why individuals who work during the night find it hard to fall asleep during the day, and consequently stay awake for the next night.

What are advantages and disadvantages of Asexual Reproduction? also write example.

Question:

What are advantages and disadvantages of Asexual Reproduction? also write example.

Answer:

Advantages of Asexual Reproduction

Following are the advantages of asexual reproduction:

• Mates not required.
• The process of reproduction is rapid.
• An enormous number of organisms can be produced in very less time.
• Positive genetic influences pass on to successive generations.
• It occurs in various environments.

Disadvantages of Asexual Reproduction

The major disadvantages of asexual reproduction are:

• Lack of diversity. Since the off springs are genetically identical to the parent they are more susceptible to the same diseases and nutrient deficiencies as the parent. All the negative mutations persist for generations.
• Since only one organism is involved, the diversity among the organisms is limited.
• They are unable to adapt to the changing environment.
• A single change in the environment would eliminate the entire species.

Asexual Reproduction Examples

Following are the examples of asexual reproduction:

• Bacterium undergoes binary fission in which the cell divides into two along with the nucleus.
• Blackworms or mud worms reproduce through fragmentation.
• Hydras reproduce through budding.
• Organisms such as copperheads undergo parthenogenesis.
• Sugarcane can be grown through vegetative propagation.

What is Asexual Reproduction? write it's type and characteristics.

Question: 

What is Asexual Reproduction? write it's type and characteristics. 

Answer:

Asexual Reproduction:

Asexual reproduction is a mode of reproduction in which a new offspring is produced by a single parent. The new individuals produced are genetically and physically identical to each other, i.e., they are the clones of their parent.

Asexual reproduction is observed in both multicellular and unicellular organisms. This process does not involve any kind of gamete fusion and there won’t be any change in the number of chromosomes either. It will inherit the same genes as the parent, except for some cases where there is a chance of rare mutation to occur.

Characteristics of Asexual Reproduction:

Following are the important features of asexual reproduction:

1. Single parent involved.
2. No fertilization or gamete formation takes place.
3. This process of reproduction occurs in a very short time.
4. The organisms multiply and grow rapidly.
5. The offspring is genetically similar.

Types of Asexual Reproduction:

There are different types of asexual reproduction:

• Binary Fission
• Budding
• Fragmentation
• Vegetative Propagation
• Sporogenesis

What is the Calorific value? and write its importance.

Question: 

What is the Calorific value? and write its importance.

Answer:

Calorific Value:

Calorific value is the amount of heat energy present in food or fuel and which is determined by the complete combustion of specified quantity at constant pressure and in normal conditions. It is also called calorific power. The unit of calorific value is kilojoule per kilogram i.e. KJ/Kg.

Water vapour is generated in the combustion process and the heat should be recovered by using certain techniques. If the heat contained in the water vapour could be recovered then it has high calorific value. If heat contained in the water vapor could not be recovered when it has low calorific value.

The efficiency of fuel or food mainly depends on the calorific value. If the value is high, its efficiency will also be high. If the value is low, its efficiency would also decrease. Calorific value is directly proportional to its efficiency.

Importance of Calorific Value:

It is very important to have a knowledge of the calorific value of fuel to carry out our day-to-day activities. This knowledge helps us to determine the amount of energy we transport. The gas shippers and suppliers require this information to bill gas consumers. It also helps to determine transportation charges of gas shippers and suppliers.

The human body requires calories to carry out daily activities. Without calories, the body would stop working and the cells in the body would die. But, if people consumed only a specific amount of calories each day, they would lead a healthy life. Too high or too low calorie consumption eventually leads to health problems.