In birds, sex is determined by a ZW chromosome scheme. Males are ZZ and females are ZW. A recessive lethal allele that causes death of the embryo is sometimes present on the Z chromosome in pigeons. What would be the sex ratio in the offspring of a cross between a male that is heterozygous for the lethal allele and a normal female?

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#Question id: 19017

#Unit 13. Methods in Biology

Which technique is also known as colour writing ?

TLS Online TPP Program

#Question id: 19018

#Unit 9. Diversity of Life Forms

which trait(s) is (are) shared by many modern gymnosperms and angiosperms? 

1. Pollen transported by wind 

2. Lignified xylem 

3. Microscopic gametophytes 

4. Sterile Sporophylls, modified to attract pollinators 

5. Endosperm 

TLS Online TPP Program

#Question id: 19019

#Unit 9. Diversity of Life Forms

Arrange the following structures, which can be found on male pine trees, from the largest structure to the smallest structure (or from most inclusive to least inclusive). 

1. sporophyte 2. microspores 

3. microsporangia 4. Pollen cone 

5. Pollen nuclei 

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#Question id: 19020

#Unit 9. Diversity of Life Forms

The main way that pine trees disperse their offspring is by using 

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#Question id: 19025

#Unit 8. Inheritance Biology

Consider the ABO “blood type” gene. This single gene has three alleles called A, B, and O. There are four resultant “blood types” (phenotypic classes), as follows: C

                         

Assume Hardy-Weinberg equilibrium,  the frequencies of the A and B alleles are 0.26 and 0.07, respectively. You now examine the ABO blood types in a new population. You observe that the A, B, and O blood types all have equal frequencies in this population. What are the frequencies of the A and O alleles in this population?

TLS Online TPP Program

#Question id: 19026

#Unit 8. Inheritance Biology

Consider the ABO “blood type” gene. This single gene has three alleles called A, B, and O. There are four resultant “blood types” (phenotypic classes), as follows:

                             

Assume Hardy-Weinberg equilibrium, the frequencies of the A and B alleles are 0.26 and 0.07, respectively. You now examine the ABO blood types in yet another population. You observe that the AB blood type has a frequency of 0.50 in this population. What are the frequencies of the A and O alleles in this population?