Facts about Blood Groups in Biology

What Are Blood Groups?

Blood groups are different kinds of blood which are determined by the presence or absence of surface antigens in an individual's red blood cells. The antigens are capable of inducing an immune response if the blood is transfused into someone with a dissimilar type of blood, such as from donor to recipient. Therefore, blood types must be suitably matched to ensure safe blood transfusions and organ transplants.

The ABO Blood Group System

The ABO blood group system is the most famous and clinically significant grouping system, whereby blood is divided into four main types: A, B, AB, and O. This classification is based on whether the A or B antigen is present or absent on the membrane surface of red blood cells.

Discovery & History

• It was discovered by Karl Landsteiner in 1901.

• Landsteiner received the Nobel Prize in Physiology or Medicine in 1930.

• ABO grouping revolutionised blood transfusion practice.

Antigens & Antibodies

• Type A: A antigens on red cells, anti-B antibodies in plasma.

• Type B: B antigens on red cells and anti-A antibodies in plasma.

• Type AB: both A and B antigens on red cells, no antibodies in plasma.

• Blood type O: No antigens on red cells, both anti-A and anti-B antibodies in plasma.

Blood Type Compatibility

• Type O negative is the universal donor.

• Type AB positive is the universal recipient.

Global Prevalence

• O is the most common globally.

• Distribution varies significantly by region and ethnicity.

Rh Blood Group System

The second, of the critical classifications, is that of the Rh blood group system, generally the Rh factor. This is also of importance during pregnancy and transfusions, consisting of the presence or absence of the D antigen, generally referred to as being Rh positive or negative.

Discovery

• 1940 by Karl Landsteiner and Alexander Wiener.

• Named after the Rhesus monkey, in which it was first identified.

• Explained hemolytic disease of the newborn.

Rh Factor (Positive Vs Negative)

• Rh positive: D antigen present on red cells.

• Rh negative: D antigen is absent on red cells.

Clinical Importance

• It is crucial in preventing Rh incompatibility reactions.

• An Rh-negative mother with an Rh-positive fetus can develop antibodies. These will have implications for the fetus in future pregnancies.

Inheritance Of Blood Groups

Blood group inheritance is passed on by alleles passed down from parents. There is a pattern of transmission of ABO and Rh blood group systems that can be predicted by the use of genetic tools.

Genetics of Blood Group Systems

• The ABO system is determined by the ABO gene, located on chromosome 9.

• The Rh system is determined by the RHD gene, located on chromosome 1.

Punnett Square

• Tool to find the probability of offspring inheriting particular blood groups.

Patterns Of Inheritance

• ABO is co-dominant. A and B are considered dominant over O.

• Rh-positive is dominant over Rh-negative.

Blood Group Testing

Blood grouping is done to ensure safe transfusions and organ transplantations. Several methods are used to identify blood groups with accuracy.

Common Testing Techniques

Blood groups can be tested using the following techniques:

• Agglutination tests

• Gel card techniques

• DNA-based methods

Procedure And Interpretation Of Results

• Sample collection of blood.

• Mixing with anti-A and anti-B antibodies for observation of the reactions.

• Reading and interpretation according to agglutination methodologies.

Safety And Precautions In Blood Group Testing

• Sterile techniques to avoid contamination.

• Correct labelling and handling of samples.

• Avoiding cross-contamination.

Blood Group Compatibility And Transfusions

Knowledge of blood-group incompatibility is essential in transfusion to prevent undesirable reactions from occurring. Proper matching makes for a safe and effective treatment.

Rules Of Compatibility

• O negative can donate to all blood types.

• AB positive can be received from all blood types.

• Matching the blood types of the donor and recipient reduces the risk of reactions.

Consequences Of Incompatible Transfusions

• Hemolytic transfusion reactions.

• Renal failure.

• Anaphylactic reactions.

Blood Groups And Health

There exist several associations of certain health aspects or conditions through blood groups, which constitute modifiers of susceptibility to and progression of diseases and responses to their treatment.

Disease Associations

Blood groups that confer increased or decreased risk for a particular disease—for instance, Type O and its associated decreased risk of cardiovascular diseases.

Transplantation Role

This is where compatibility plays a very important factor in organ transplants to avoid organ rejection.

Importance Of Blood Donation

Blood donation is a life-saving process. The processes involved and the knowledge of the importance of its correct storage mean that blood donated is put to good use.

• Loss of life can be avoided in emergencies and the cases of patients suffering from various illnesses.

• It sustains the crucial supply needed for surgeries and treatment.

Top 10 Facts About Blood Groups

10 important facts about blood groups are:

• Blood groups depend on antigens present on RBCs.

• The ABO system was discovered by Karl Landsteiner in 1901.

• O negative is a universal donor.

• AB positive is a universal recipient.

• Rh factor was discovered in 1940 in the Rhesus monkey.

• Blood groups vary by ethnicity & region.

• Incompatible transfusion can lead to deadly immune reactions.

• Rh incompatibility can harm future pregnancies.

• ABO & Rh groups follow predictable genetic inheritance.

• Blood group testing uses agglutination, gel cards and DNA analysis.

Facts about Blood Groups NEET MCQs (With Answers & Explanations)

This is an important topic and carries significant weightage in NEET exam. Types of questions asked from this topic are:

• ABO and Rh Blood Group System

• Facts about blood groups

Practice Questions for NEET

Q1. Which instrument is used to determine the red cell count?

1. Haemocytometer

2. Haemoglobinometer

3. Electrocardiogram

4. Sphygmomanometer

Correct answer: 1) Haemocytometer

Explanation:

Red cell count measures the number of red blood cells in a given volume of blood. It is typically carried out using a device called a hemocytometer. A hemocytometer is a specialized microscope slide with a grid pattern etched onto its surface. By diluting a small volume of blood and placing it on the hemocytometer, the red blood cells can be counted under a microscope, allowing for the determination of the red cell count.

Explanation for incorrect options :

Option (2)The Haemoglobinometer is incorrect because it is a device used to measure the concentration of haemoglobin in the blood, not the red cell count.

Option (3) Electrocardiogram (ECG) is a diagnostic tool used to record the electrical activity of the heart, and it is not directly involved in determining red cell count.

Option (4) Sphygmomanometer is a device used to measure blood pressure, and it is not used for red cell count assessment.

Hence, the correct answer is option 1) Haemocytometer.

Q2. There is no DNA in:

1. Mature RBCs

2. Mature spermatozoan

3. Hair Root

4. An enucleated ovum

Correct answer: 1) Mature RBCs

Explanation:

As we learnt in

RBCs -

RBCs are formed in the red bone marrow in adults. RBCs lack nuclei in most mammals and are biconcave in shape.

- wherein

They have a red-coloured, iron-containing complex protein called haemoglobin, hence the colour and name of these cells. A healthy individual has 12-16 gms of haemoglobin in every 100 ml of blood.

Mature RBCs are devoid of nucleus and DNA is absent.

Hence, the correct answer is option 1) mature RBCs.

Q3. Assertion: Eosinophils play a role in the destruction of parasitic forms.

Reason: Eosinophils can bind to parasitic forms and induce their destruction by releasing lysosomal enzymes from their surface.

1. The assertion is true, and the reason is false.

2. The assertion is false, and the reason is true.

3. Both the assertion and reason are true and are correctly related.

4. The assertion is true, but the reason does not provide a valid explanation.

Correct answer: 3) Both the assertion and reason are true and are correctly related.

Explanation:

The assertion states that eosinophils contribute to the destruction of parasitic forms, which is true. Eosinophils are a type of white blood cell that plays a role in the immune response against parasitic infections.

The reason is that eosinophils can attach themselves to parasitic forms and initiate their destruction by releasing lysosomal enzymes from their surface. This is also true. Eosinophils have specific surface receptors that allow them to bind to parasites. Upon attachment, they release toxic granules containing enzymes, such as major basic proteins, eosinophil peroxidase, and eosinophil-derived neurotoxin, which can damage and kill the parasites.

Hence, the correct answer is option 3) Both the assertion and reason are true and are correctly related.

Also Read-

• MCQs on Composition of Blood

• Cardiac Cycle

• Facts about Blood

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