How to use a key, Biology

Assignment Help:

Q. How to Use a Key?

The use of a key is analogous to travelling a high way, that forks repeatedly, each fork having roadside directions. If a traveller follows the proper directions, the destination will be reached

The first step in identification of an unknown plant involves the use. of keys to determine the family, next is the key to genera which will provide the generic name. After the genus is determined the keying process is repeated within the genus for a determination of the species.

If a number of plants ABCDEFG is given to you for identification, you have to place them in two group viz. Dicots and Monocots with the aid of keys already given to you. The characters that you have to study for their grouping are that of a) Leaves - their venation, b) flower - the number of floral parts, c) embryos - the number of colyledons.

Carry out the study of these characters in the plants provided to you and record these. Suppose in case of plant ACEF the answer given to three characters given in the key is identical to those mentioned in lead, these belong to dicots i, e. their leaves have a reticulate venation, their flowers are pentamerous or tetramerous and the number of cotyledons is 2 while in plant BD and G characters are identical to those mentioned in lead 1 i.e. leaves have a parallel venation, flowers are trimerous and the embryos,
have only one cotyledon, these belong to monocots.

Further classification of plants into three series of Dicots viz. Monochlamydeae, Polypetalae and Gamopetalae is possible by ascertaining the presence or absence of characters mentioned in leads 2 and 3 in the key 2 para 3.

While using a key

i) understand the terms clearly and use proper terms.

ii) Read both the leads (clues) of a couplet carefully. When the answer to one lead is positive and that of the alternative lead is negative. You are on correct lines, If the answer is positive or negative in both the cases there is some mistake.

iii) If the alternatives in the couplets are not clear and contrasting but these overlap, make the conclusion after checking the description matching with identified species,

iv) While checking the measurements of organs mentioned in the key, measure more than one such parts preferably in 3 replicates and take an average. You should understand that there is a variation in size in-fresh and dried specimens.


Related Discussions:- How to use a key

Flame cells, where are flame cells present?

where are flame cells present?

Why do some physicians advise patients, Why do some physicians advise patie...

Why do some physicians advise patients with a bladder infection to drink a lot of cranberry juice? Answer Cranberry juice contains chemicals that kill viruses and bacteria. The inc

Explain the uses of iso in dairy-type products, Normal 0 false ...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

What is peaked t-waves, Q. What is Peaked T-Waves? Exercise induced inc...

Q. What is Peaked T-Waves? Exercise induced increase in T-wave amplitude in V2 is quite predictive of anterior wall ischaemia (specificity = 95 percent). It appears that this m

Draw a graph for an iv multiple infusion of a drug, Draw A graph for an IV ...

Draw A graph for an IV multiple infusion of a drug, and label on the graph where the trough (predose) blood draw would be collected and where the peak (postdose) blood draw would b

Importance of pituitary gland, Importance of pituitary gland Pitutar...

Importance of pituitary gland Pitutary gland is very small and it is about the size of a large pea seed. It is very important as it controls the functions of all the othe

Define types of dryers, Define types of Dryers? There are many other dr...

Define types of Dryers? There are many other dryer types available, such as; Osmotic Drying Impingement Drying Microwave and Dielectric Drying Superheated

Lab safety, Why should you not apply cosmetics while doing a lab experiment...

Why should you not apply cosmetics while doing a lab experiment in class?

What are the main endocrine glands of the human body, What are the main end...

What are the main endocrine glands of the human body? The major endocrine glands of the human body are the pineal gland (or pineal body), the hypophysis (or pituitary), the thy

Hormones of pancreas, HORMONE S OF PANCREAS AND THEIR ROLE - (i) Glu...

HORMONE S OF PANCREAS AND THEIR ROLE - (i) Glucagon (Secreted by a-cells) It stimulates the liver to convert stored glycogen into glucose. Glucagon is controlled b

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd