Question

to create a punnett square, perform the following steps: 1. take the factors from the first parent and place them at the top of the square (b and b). 2. take the factors from the second parent and line them up on the left side of the square. 3. pull the factors from the top into the boxes below. 4. pull the factors from the side into the boxes next to them. the possible offspring are represented by the letters in the boxes, with one letter coming from each parent. results: top left box: bb, or purple flowers top right box: bb, or purple flowers lower left box: bb, or purple flowers lower right box: bb, or white flowers only one of the plants out of the four, or 25% of the plants, has white flowers (bb). the other 75% have purple flowers (bb, bb), because the purple factor (b) is the dominant factor. this shows that the color purple is the dominant trait in pea plants. now imagine you cross one of the white flowers (bb) with a purple flower that has both a dominant and recessive factor (bb). the only possible gamete in the white flower is recessive (b), while the purple flower can have gametes with either dominant (b) or recessive (b). practice using a punnett square with this cross (see table and punnett square below). practice using a punnett square with this cross below. did you find that 50% of the offspring will be purple, and 50% of the offspring will be white? circle one: yes or no (1 point) use these punnett squares to complete review questions review questions (2 points each): 1. in peas, yellow seeds (y) are dominant over green seeds (y). if a yy plant is crossed with a yy plant, what ratio of plants in the offspring would you predict? 2. in guinea pigs, smooth coat (s) is dominant over rough coat (s). if an ss guinea pig is crossed with an ss guinea pig, what ratio of guinea pigs in the offspring would you predict?

Explanation:

Step1: Set up Punnett - square for yy and YY cross

The possible gametes for yy are y, and for YY are Y. In a Punnett - square, we have 2 rows and 2 columns. The top of the square has Y (from YY) and the side has y (from yy).

Step2: Fill in Punnett - square

When we combine the gametes, we get Yy in all 4 boxes of the Punnett - square. So the ratio of plants in the offspring is 100% Yy (all yellow - seeded plants), or the ratio of yellow - seeded : green - seeded plants is 4:0 or 1:0.

Step3: Set up Punnett - square for SS and ss cross

The possible gametes for SS are S, and for ss are s. In a Punnett - square, with 2 rows and 2 columns, the top has S (from SS) and the side has s (from ss).

Step4: Fill in Punnett - square

When we combine the gametes, we get Ss in all 4 boxes of the Punnett - square. So the ratio of guinea pigs in the offspring is 100% Ss (all smooth - coated guinea pigs), or the ratio of smooth - coated : rough - coated guinea pigs is 4:0 or 1:0.

Answer:

1. 1:0 (all yellow - seeded plants)
2. 1:0 (all smooth - coated guinea pigs)