Worksheet featuring dihybrid cross problems with Punnett squares for plant flower color and height, and guinea pig fur color and texture.

Final Answer:
All offspring will be tall with purple flowers (genotype FfDd). The probability for each part in question 2 is:
a) 100% — Tall plants with purple flowers (FfDd)
b) 0% — No short plants with pink flowers
c) 0% — No short plants with purple flowers
d) 0% — No tall plants with pink flowers

For question 3, the Punnett square has 16 boxes with combinations of B/b and R/r. The probabilities are:
a) 9/16 — Black, rough fur (BBRR, BBRr, BbRR, BbRr)
b) 3/16 — Black, smooth fur (BBrr, Bbrr)
c) 3/16 — White, rough fur (bbRR, bbRr)
d) 1/16 — White, smooth fur (bbrr)

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Explanation:
Let’s go step by step.

Question 1:
We’re crossing two parents:
- One is FFDD → this means it has only dominant alleles (purple + tall)
- The other is ffdd → this means it has only recessive alleles (pink + short)

Each parent can only give one type of allele combination:
- FFDD gives only FD
- ffdd gives only fd

So every child gets one FD and one fd → that makes FfDd for all kids.
That means every plant will be tall (because D is dominant) and purple (because F is dominant).

Now Question 2:
a) Tall + Purple → All kids are FfDd → so 100% chance. Genotype: FfDd
b) Short + Pink → That would need ffdd → but no kid gets that → 0%
c) Short + Purple → Needs ffD_ → no kid has ff → 0%
d) Tall + Pink → Needs F_dd → no kid has dd → 0%

Question 3:
Now we cross two heterozygous guinea pigs: BbRr x BbRr
Each parent can make 4 types of gametes: BR, Br, bR, br
So we make a 4x4 grid (16 squares total)

Fill in the grid:
Top row: BR, Br, bR, br
Left column: same

Then combine them:

Example: BR + BR = BBRR
BR + Br = BBRr
Br + bR = BbRr
... and so on.

Now count how many have:
a) Black + Rough → needs at least one B and one R → 9 out of 16
b) Black + Smooth → needs B and rr → 3 out of 16
c) White + Rough → needs bb and R → 3 out of 16
d) White + Smooth → needs bb and rr → 1 out of 16

That’s how you get the answers!

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