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PRACTICAL ACTIVITIES TO DEMONSTRATE CONTINUOUS VARIATIONS

PRACTICAL ACTIVITIES TO DEMONSTRATE CONTINUOUS VARIATIONS

Height of students

  • Students should work in pairs, use chalk and metre rule to mark level of top of head onto the wall.
  • Or door as one student stands straight without shoes, next to the wall or door.
  • The height for each student is recorded on chalk board.
  • The frequency distribution of height is recording as the height is grouped into various classes.
  • A histogram to represent frequency against height is drawn.
  • The normal bell shaped curve is observed.

 

Discontinuous variations – ability to roll tongue

  • The number of students who can roll their tongue is recorded as well as the number of non-tongue rollers.
  • The ratio of tongue-rollers to non-tongue rollers is worked out.
  • Gene for the ability to roll the tongue is dominant, therefore is expected more tongue rollers.

 

Demonstration of Mitosis and Meisosis

Mitosis

  • Plasticene is used to represent number and shapes of various chromosomes e.g. 8 in Drosophila melanogaster.
  • Each stage of mitosis illustrated e.g. interphase.
  • Each is rolled to appear long is and coiled, prophase is each made into a ball and then shaped to the appropriate length; and split into two to represent chromatids.
  • Centromeres for different chromosomes can be illustrated in different positions.
  • Each stage of mitosis is illustrated and telophase can be illustrated by surrounding the “chromosomes” with a long many drawn plasticene to represent cell membrane.
  • It is manipulated to show how telophase takes place.

 

Meiosis

  • The same procedure is followed.
  • Plasticine with contrasting colours is used to show clearly gene mixing in crossing over.
  • Each pair of homologous chromosomes is represented by plasticene with two different colours e.g. red (paternal) blue for maternal chromosome.
  • All the steps in the two stages of meiosis are illustrated up to the production of four haploid gametes.

 

Human Finger Prints

  • The finger prints for each student’s thumb, forefinger and middle fingers of the left hand are imprinted on a white paper.
  • A rubber stamp with ink is used to and each finger -tip phalange is rolled onto the inkpad.
  • For best results students work in pairs.
  • Observations are made at all forefingers, thumb prints and differences noted.
  • The main patterns are noted. It is also noted that no two, fingerprints are exactly similar.

 

See also

GENETIC ENGINEERING

PRACTICAL APPLICATIONS OF GENETICS

LINKAGE

COMPLETE AND INCOMPLETE DOMINANCE

MUTATIONS

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