Lethal Alleles and Their Effects

What is the main topic of the video tutorial?

• Photosynthesis

• Cell Division

• Human Anatomy

• Mendel's First Law and its variations

What are lethal alleles?

• Alleles that cause death in the embryonic stage or at birth

• Alleles that enhance survival

• Alleles that only affect plant species

• Alleles that have no effect on the organism

How do lethal alleles affect Mendelian ratios?

• They do not affect Mendelian ratios

• They cause a 1:1 ratio

• They cause a 4:1 ratio

• They alter the classic 3:1 phenotypic ratio

What is a characteristic of a lethal dominant allele?

• It is only lethal in homozygous form

• It is always beneficial

• It is lethal in heterozygous form

• It has no effect on the organism

In the case of coat color in mice, what happens when the dominant allele is in homozygous form?

• The mice are unaffected

• The mice do not survive

• The mice have enhanced survival

• The mice are born with a different color

What is the phenotypic ratio observed in the coat color of mice due to lethal alleles?

• 3:1

• 1:1

• 4:1

• 2:1

What genetic condition in humans is used as an example of lethal alleles?

• Huntington's disease

• Achondroplasia

• Cystic fibrosis

• Sickle cell anemia

What is the phenotypic ratio observed in achondroplasia due to lethal alleles?

• 4:1

• 2:1

• 3:1

• 1:1

Why are there no documented cases of homozygous dominant individuals with achondroplasia?

• They do not survive to adulthood

• They are unaffected

• They are always healthy

• They have a different condition

What should you consider when solving exercises involving lethal alleles?

• The 4:1 ratio

• The classic 3:1 ratio

• The altered 2:1 ratio

• The 1:1 ratio