Hi, I hope this helps:<br />
Equipment and materials<br />
• Beakers<br />
• Black beads (B)<br />
• White beads (b)<br />
Method for investigating the way in which alleles<br />
are inherited<br />
1 The black beads represent dominant alleles (B) and the white beads recessive alleles (b).<br />
2 Visit the 4 stations; A, B, C and D.<br />
Station A: beaker of black beads, beaker of white beads<br />
Station B: beaker of black beads, beaker of equally mixed black and white beads, 2 empty beakers.<br />
Station C: beaker of white beads, beaker of equally mixed black and white beads, 2 empty beakers.<br />
Station D: Two beakers of equally mixed black and white beads, 3 empty beakers.<br />
3 At A, you have a beaker containing black beads and a beaker containing white beads. If you take one bead from each beaker, what is the genotype and the phenotype of the offspring?<br />
4 At B, there is a beaker full of black beads and a beaker containing black and white beads mixed together in equal numbers. In front of the beakers, there are two empty containers. With your eyes closed, take a bead from each beaker. Look at your selection and if they are both black put them in the right hand container. If one is black and one is white, put them in the left hand container. Repeat this until you have made 20 choices. Count and record the number of pairs of beads in each beaker. Replace the pairs of black beads in their original beaker. Similarly, replace the pairs of black and white beads in the beaker of mixed beads.<br />
5 At C, there is a beaker of white beads, a beaker of mixed beads and two empty containers as before. Repeat the procedure used at B, counting and recording the number of pairs of beads in each beaker. Replace the beads in their correct beakers as before.<br />
6 At D, there are two beakers each containing equal numbers of black and white beads. In front of the beakers there are three empty containers. With your eyes closed, select one bead from each beaker. Look at your selection: if you have two black beads, place them in the right hand container; if you have two white beads, place them in the left hand container; if you have one black and one white, place them in the middle container. Repeat until you have made 20 choices. Count and record the pairs of beads in each container. Return the beads to the containers, making sure that equal numbers of black and white beads are restored.<br />
Results<br />
Tabulate your results for each situation sampled.<br />
Using the letters B and b to represent the alleles, write out the crosses represented by A, B, C, and D, clearly identifying the genotypes and phenotypes in each case.<br />
Work out the ratios of the genotypes and the phenotypes for each cross.
