Category Archives: Forensic Botany

Passage related MCQ

Read the paragraph and answer the objective questions given at the end of it:

In summer a decomposed unidentified dead body was found floating in a river. The postmortem examination revealed the presence of weeds in the hand of the deceased. The internal examination of deceased body showed the presence of froth in trachea and diatoms in the lungs.

1. The floating of dead body shows that the death was caused:

A.) Within 4 hours

B.) 4 to 13 hours

C.) 12 to 24 hours

D.) More than 3-4 days

2. The presence of _____ will ascertain that it is an antemortem drowning:

A.) Weed in hands

B.) Diatoms in lungs

C.) Froth in trachea

D.) All of the above

3. The identification of dead body can be done by:

A.) Putrefied body

B.) Place of occurrence

C.) Laundry and tailor marks on clothes

D.) None of the above

4. The fingerprint of the deceased can be obtained by:

A.) Visual Examination

B.) Infrared Photography

C.) X-Ray Photography

D.) UV Photography

Answers : 1. C 2. D 3. C 4. A


Diatoms are microscopic unicellular, photosynthetic, eukaryotic algae that inhabit almost all bodies of water.

They are found in springs, rivers, ponds, lakes, ditches and in freshwater and marine waters and occur in terrestrial habitats such as wet rocks, mosses and soils, even caves.

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Domain – Eukaryota

Kingdom- Chromalveolata

Phylum- Heterokontophyta

Class –Bacillariophyceae

Orders- Centrales & Penales

Diatoms have traditionally been classified according to the shape of their valves, divided into two major structural groups:

  • Centric Diatoms (With valves exhibiting a radial symmetry)
  • Pennate Diatoms (With valves exhibiting bilateral symmetry)


When a dead-body is recovered from water, there is always a question whether it was a case of ante-mortem or post-mortem drowning i.e. whether the body was drowned before or after death. In these medico legal cases, presence of diatoms in the body tissues is very useful evidence.

It helps to differentiate a death by submersion from an immersion of a body.

Laboratory tests may reveal the presence of diatoms in the body.

Their silica-based skeletons do not readily decay and they can sometimes be detected even in heavily decomposed bodies.

If the person is dead when entering the water, then there is no circulation and the transport of diatom cells to various organs is prevented because of a lack of circulation and diatoms cannot enter the body.

If the person is still alive when entering the water, diatoms will enter the lungs if the person inhales water and drowns. The diatoms are then carried to distant parts of the body such as the brain, kidneys, and bone marrow by circulation.

Since diatoms resist putrefaction, the diatom test is particularly valuable, where decomposition is advanced. Diatom test is negative in dead bodies thrown in water and in dry drowning.

Forensic Limnology

Forensic limnology is a sub-field of forensic botany. this field mainly examines the presence of diatoms in crime scene samples and victims.


Materials taken from victims/suspects/crime scene or Environmental products, i.e. mud

  • Keep in a Test tube with a sulfuric acid and potassium dichromate solution for 24 hours.
  • Centrifuge The Tube.
  • Placed in A boiling water bath for an hour.
  • Pellet Is Extracted.
  • Mixed with distilled water.
  • mounted on a slide with Hyrax.
  • Use phase contrast microscopy for observing Diatoms.

Diatoms have to be cleaned before examination so that any foreign material can not interfere with microscope examination.

The use of diatoms as a diagnostic test for drowning is based upon the hypothesis that diatoms will not enter the systemic circulation and be deposited in such organs as the bone marrow unless the circulation is still functioning thus implying that the decedent was alive in the water.

for the detection and examination of diatom , Hard bones (sternum and femur) and soft tissues (lungs and liver etc.) of drowned bodies are usually sent to the Forensic Science Laboratories.


It’s a faster and less expensive Test. The Soluene-350 method is used only for freshwater samples.

  • The sample should mixed with formalin, rinsed and centrifuged three times with distilled water. 
  • The pellet should removed from the test tube added with 8ml of Soluene-350.
  • After that it should Incubated at 50 degrees Celsius for 2 hours
  • Then it should Centrifuged again.
  • After all the process it should be Mounted on a slide to see under microscope.


The ‘’’Enzymatic method’’’ is used for tissue samples.

Because of the use of enzyme chemicals it has a smaller percentage of damaging the diatoms collected than acid digestion method.

  • In this method Concentrated Nitric acid and Proteinase-K, or peroxide, should add to the sample for 12 hours,
  • The sample should be Centrifuged Twice before further process.
  • After that it should Rinsed with distilled water
  • Then it should Mounted on a slide with Naphrax
  • After all the process use a light microscope when examining the results.


  • Colloidal Silica Gradient Centrifugation method can be used with liver and lung samples.
  • The collected tissue is added to saline solution, centrifuged at a temperature of 12 degrees Celsius.
  • Then distilled water should be distilled water
  • Then it should be mounted on a slide and observed.


  • The ‘Membrane Filter method’ is used when there is a presence of either damaged diatoms in the sample (result of pollutants) or inorganic materials.
  • The blood of the victim should be taken and filtered through Sodium Dodecyl Sulfate and nitrocellulose membranes with decreasing pore sizes.
  • The membranes will be dry and filter with distilled water.
  • After being dried the pieces of membrane that filtered the blood, should be examined for diatoms and pollen grains.


‘Dry Ash method’ can only be applied to a bone marrow sample.

Five grams of marrow should be taken from a victim to be placed in a nitric acid solution and then burnt in a furnace allowing the release of diatoms to then be analyzed. whether the body was drowned before or after death. In these medico legal cases, presence of diatoms in the body tissues is very useful evidence.


  • Samples should be collected from the suspected drowning victim. Care should be taken as to not contaminate the sample with foreign diatoms during the process.
  • For example, Intact femurs are removed at autopsy and washed in distilled water. Femurs are longitudinally sectioned using a clean band saw, and the bone marrow about 50g is removed using a clean spatula and placed into a boiling flask.
  • Approximately 50 mL of conc. nitric acid need to be added to the flask, and the marrow-acid suspension will be boiled on a hot plate for approx 48 hours-under a fume hood.
  • The suspension should be cooled and centrifuged, in some instances at two different times, the supernatant should be discarded and the resulting acid-resistant material dropped onto a clean microscope slide and the sediment examined under the microscope Should be done.


  • First all calcareous compounds have been removed so that the sample will not form gypsum crystals.
  • When sample has settled completely then discard supernatant.
  • Add conc. sulphuric acid until the volume is twice.
  • Just add enough Potassium bichromate to make for a saturated solution.
  • Let stand for 24 hours or more, or speed up the reaction in a water-bath 60 degrees. The sediment should look grayish.
  • Let settle completely, discard supernatant and rinse several times.


Electron or dark phase microscopy is currently the main methods used for analysis. In order to examine the morphology of diatoms, both transmission and scanning electron microscopes are able to provide a much more detailed image. These microscopes were necessary for taxonomic purposes, with the distinctions between species being so minute at times.

Scanning Electron Microscopy (SEM)

SEM is best for visualizing the entire diatom Frustule. It is a device that can visualize the gross morphology of the diatom’s both internal and external parts.

Transmission Electron Microscopy (TEM)

This type of microscopy is best. with the help of this device we can see the finer, delicate details of the diatom frustule.

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Cannabis is derived from the cannabis plant (cannabis sativa). It grows wild in many of the tropical and temperate areas of the world.

Cannabis is a drug that comes from Indian hemp plants such as Cannabis sativa and Cannabis indica.


  • Cannabis is a depressant drug.
  • They slow down the activity of the central nervous system and the messages going between the brain and the body.
  • When large doses of cannabis are taken it may also produce hallucinogenic effects.

Cannabis Appearance

Leaves from the cannabis plant are bright green and have a distinctive shape with five or seven leaflets. The flowering tops and upper leaves are covered in a sticky resin.

Cannabis Also Known As:

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The main active ingredient in cannabis is called delta-9 tetrahydro-cannabinol, commonly known as THC. This is the part of the plant that gives the “high.”There is a wide range of THC potency between cannabis products.

Cannabis Is Used In Three Main Forms:

1. Marijuana

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  • Marijuana is the most common and least potent form of cannabis. Marijuana is the dried leaves and flowers of the plant.
  • It is smoked in hand-rolled cigarettes (joints), or in a pipe (a bong).

2. Hashish

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  • Hashish (“hash”) is dried cannabis resin, usually in the form of a small block. The concentration of THC in hashish is higher than in marijuana, producing stronger effects.
  • It is usually added to tobacco and smoked, or baked and eaten in foods such as hash cookies.

3. Hash Oil.

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  • Hash oil is a thick, oily liquid, golden brown to black in colour, which is extracted from cannabis. Hash oil is the strongest form of cannabis.
  • It is usually spread on the tip or paper of a cigarette and then smoked.

Short-Term Effects of Cannabis

  • Dryness of the eyes, mouth, and throat;
  • Feeling of well-being;
  • Talkativeness;
  • Drowsiness;
  • Loss of inhibitions;
  • Decreased nausea;
  • Increased appetite;
  • Loss of co-ordination;
  • Bloodshot eyes;
  • Anxiety and paranoia.

Long-Term Effects of Cannabis

  • Increased risk of respiratory diseases associated with smoking, including cancer;
  • Decreased memory and learning abilities;
  • Decreased motivation in areas such as study, work or concentration.

Medical Uses

Cannabis has been used for medical purposes for many centuries. It has been reported that cannabis may be useful to help conditions such as:

  • Wasting And Severe Weight Loss, In People With HIV/AIDS, Cancer, Or Anorexia Nervosa, As It May Be Used As An Appetite Stimulant.
  • Nausea And Vomiting, Particularly When Associated With Chemotherapy.
  • Pain Relief, For Example In People With Cancer And Arthritis.
  • Relief From Symptoms Of Some Neurological Disorders That Involve Muscle Spasms, Including Multiple Sclerosis And Spinal Cord Injury.
  • Asthma.
  • Epilepsy
  • Glaucoma

Cannabis is consumed in many different ways:

  • Vaporizer, which heats any form of cannabis to 165–190 °C (329–374 °F), causing the active ingredients to evaporate into A vapor without burning the plant material (the boiling point of THC is 157 °C (315 °F) at 760 mmhg pressure).
  • Smoking, which typically involves burning and inhaling vaporized cannabinoids (“smoke”) from small pipes, bongs (portable versions of hookahs with A water chamber), paper-wrapped joints or tobacco-leaf-wrapped blunts, etc.
  • Cannabis tea, which contains relatively small conc. Of THC because THC is an oil (lipophilic) and is only slightly water-soluble (with A solubility of 2.8 mg per liter).
  • Cannabis is added as an ingredient to one of A variety of foods, including butter and baked goods. In india it is commonly made into A beverage, bhang.
  • Capsules, typically containing cannabis oil, and other dietary supplement products.

Substance prepare from cannabis:

  • Marijuana

Marijuana or marihuana (herbal cannabis), consists of the dried flowers and subtending leaves and stems of the female Cannabis plant. This is the most widely consumed form, containing 3% to 20% THC, with reports of up-to 33% THC.

  • Kief

Kief is a powder, rich in trichomes, which can be sifted from the leaves and flowers of cannabis plants and either consumed in powder form or compressed to produce cakes of hashish. The word “kif” derives from colloquial Arabic كيف kēf/kīf, meaning pleasure.

  • Hashish

Hashish (also spelled hasheesh, hashisha, or simply hash) is a conc. resin cake or ball produced from pressed kief, the detached trichomes and fine material that falls off cannabis flowers and leaves. or from scraping the resin from the surface of the plants and rolling it into balls. It varies in color from black to golden brown depending upon purity and variety of cultivar it was obtained from. It can be consumed orally or smoked, and is also vaporised, or ‘vaped’. The term “rosin hash” refers to a high quality solventless product obtained through heat and pressure.

  • Tincture of cannabis

Cannabinoids can be extracted from cannabis plant matter using high-proof spirits (often grain alcohol) to create a tincture, often referred to as “green dragon”. Nabiximols is a branded product name from a tincture manufacturing pharmaceutical company.

  • Hash oil

Hash oil is a resinous matrix of cannabinoids obtained from the Cannabis plant by solvent extraction, formed into a hardened or viscous mass. Hash oil can be the most potent of the main cannabis products because of its high level of psychoactive compound per its volume, which can vary depending on the plant’s mix of essential oils and psychoactive compounds.

Detection Of Cannabis In Body Fluids

  • THC and its major (inactive) metabolite, THC-COOH, can be measured in blood, urine, hair, oral fluid or sweat using chromatographic techniques as part of a drug use testing program or a forensic investigation of a traffic or other criminal offense.
  • Urine contains predominantly THC-COOH, while hair, oral fluid and sweat contain primarily THC. Blood may contain both substances, with the relative amounts dependent on the recency and extent of usage.
  • The concentrations obtained from such analyses can often be helpful in distinguishing active use from passive exposure, elapsed time since use, and extent or duration of use.
  • These tests cannot, however, distinguish authorized cannabis smoking for medical purposes from unauthorized recreational smoking.

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