RRB Lab Technician flashcards

31 cards. Read the term and the definition here. The deck at the top of this page is optional.

Harmonic mean speed

Average speed over two equal distances travelled at speeds a and b equals 2ab/(a + b), which is always less than the arithmetic mean of the two speeds.

Compound interest formula

Amount = P(1 + R/100)^T, where P is principal, R the annual rate and T the time in years; interest is the amount minus principal.

Work rate addition

If two workers finish a job in x and y days alone, their combined rate is 1/x + 1/y per day, so together they need xy/(x + y) days.

Cylinder surface area

For a right circular cylinder of radius r and height h, curved surface area is 2πrh and total surface area is 2πr(r + h).

Opposite letter pairs

In the alphabet, letters equidistant from the two ends sum to 27: A pairs with Z, B with Y, C with X, and so on through M and N.

Syllogism validity rule

A conclusion is valid only if it holds in every possible Venn diagram consistent with the premises; one counterexample diagram makes it invalid.

Circular seating orientation

When all people face the centre, a person's left is clockwise; when all face outward, left and right are reversed relative to the circle.

Calendar odd days

A normal year shifts the weekday by one odd day, a leap year by two; 100 years give five odd days and 400 years give none.

Constitution adoption dates

The Constitution of India was adopted by the Constituent Assembly on 26 November 1949 and came into force on 26 January 1950.

RBI establishment

The Reserve Bank of India began operations on 1 April 1935 and was nationalised in 1949; it issues currency and conducts monetary policy.

Tropic of Cancer states

The Tropic of Cancer crosses eight Indian states, including Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand, West Bengal, Tripura and Mizoram.

Ohm's law

Current through a conductor is directly proportional to the potential difference across it at constant temperature: V = IR, with R in ohms.

pH definition

pH equals the negative logarithm of hydrogen ion concentration; values below 7 are acidic, 7 is neutral and above 7 is basic.

Photosynthesis equation

Six molecules of carbon dioxide plus six of water, using light energy and chlorophyll, yield one glucose molecule and six oxygen molecules.

Hardness of water

Hardness is caused by dissolved calcium and magnesium salts; temporary hardness from bicarbonates is removed by boiling, permanent hardness requires softening.

Memory unit conversions

One byte equals eight bits; one kilobyte is 1024 bytes, one megabyte is 1024 kilobytes and one gigabyte is 1024 megabytes.

RAM versus ROM

RAM is volatile working memory that loses contents on power loss; ROM is non-volatile and stores firmware such as the boot instructions.

Default network ports

HTTP uses port 80, HTTPS uses port 443, FTP uses 21, SMTP uses 25 and DNS uses port 53 for standard service traffic.

Absolute cell reference

In a spreadsheet, $A$1 is an absolute reference that does not change when copied, while A1 is relative and adjusts to the new position.

Order of draw

Blood culture first, then citrate coagulation tube, serum tube, heparin tube, EDTA tube and finally fluoride-oxalate tube for glucose.

Citrate tube ratio

Coagulation tubes contain 3.2% sodium citrate at a blood-to-anticoagulant ratio of 9:1; underfilling prolongs clotting times falsely.

Autoclave conditions

Steam sterilisation is achieved at 121 degrees Celsius and 15 psi pressure for 15 to 20 minutes, which denatures microbial proteins.

EDTA anticoagulant action

EDTA chelates calcium ions, blocking the coagulation cascade; it is the preferred anticoagulant for blood counts but not for chemistry or coagulation tests.

MCV anaemia classification

Mean corpuscular volume below 80 fL indicates microcytic anaemia, 80 to 100 fL normocytic, and above 100 fL macrocytic anaemia.

Normal haemoglobin values

Reference haemoglobin is roughly 13 to 17 g/dL in adult men and 12 to 15 g/dL in adult women; haematocrit is about three times haemoglobin.

Westergren ESR values

Normal erythrocyte sedimentation rate is up to 15 mm/hour in men and 20 mm/hour in women, rising with inflammation, infection and pregnancy.

Gram stain result

Gram-positive organisms retain crystal violet and appear purple due to thick peptidoglycan; Gram-negative organisms lose it and appear pink after counterstain.

MacConkey agar purpose

MacConkey agar inhibits Gram-positive growth and differentiates lactose fermenters, which form pink colonies, from non-fermenters, which remain pale.

Cardiac troponin use

Troponin I and T rise within hours of myocardial injury and stay elevated for days, making them the preferred markers of acute myocardial infarction.

Ziehl-Neelsen stain

Acid-fast staining with carbol fuchsin and acid-alcohol decolourisation identifies mycobacteria, which retain the red stain against a blue background.

Fasting glucose threshold

Fasting plasma glucose of 126 mg/dL or more on two occasions, or a random value of 200 mg/dL with symptoms, supports a diagnosis of diabetes mellitus.