Podcast
Questions and Answers
What was Nettie Stevens's primary contribution to the field of biology?
What was Nettie Stevens's primary contribution to the field of biology?
- Proving that nutrition affects embryonic development.
- Developing new methods for studying insect behavior.
- Discovering that sex is determined by specific chromosomes. (correct)
- Identifying the role of external factors in sex determination.
Before Nettie Stevens's discovery, what was a common belief regarding sex determination in organisms?
Before Nettie Stevens's discovery, what was a common belief regarding sex determination in organisms?
- Sex was determined solely by genetic factors.
- Sex was determined by external factors during the embryonic stage. (correct)
- Sex determination was random and unpredictable.
- Sex was determined by the presence of specific hormones.
Which institution did Nettie Stevens NOT attend?
Which institution did Nettie Stevens NOT attend?
- University of Chicago (correct)
- Bryn Mawr College
- Stanford University
- Carnegie Institute
What key observation did Nettie Stevens make regarding the chromosomes of mealworms?
What key observation did Nettie Stevens make regarding the chromosomes of mealworms?
Why might Nettie Stevens's work have been overshadowed during her lifetime?
Why might Nettie Stevens's work have been overshadowed during her lifetime?
Which statement best characterizes the relationship between Nettie Stevens and Thomas Hunt Morgan?
Which statement best characterizes the relationship between Nettie Stevens and Thomas Hunt Morgan?
Suppose a newly discovered insect species has three distinct sex chromosomes: W, X, and Y. Females can be XW or XY, while males are always XX. If a XW female mates with a XX male, what is the probability that the offspring will be female?
Suppose a newly discovered insect species has three distinct sex chromosomes: W, X, and Y. Females can be XW or XY, while males are always XX. If a XW female mates with a XX male, what is the probability that the offspring will be female?
Nettie Stevens's research provided key data to support the theory of chromosomal inheritance. Imagine scientists discovered a species where chromosomal inheritance appeared to be random, with offspring inheriting chromosomes not directly from parents but from a pool of genetic material. Assuming all other known inheritance mechanisms are ruled out, which fundamental principle of modern genetics would this discovery challenge the most?
Nettie Stevens's research provided key data to support the theory of chromosomal inheritance. Imagine scientists discovered a species where chromosomal inheritance appeared to be random, with offspring inheriting chromosomes not directly from parents but from a pool of genetic material. Assuming all other known inheritance mechanisms are ruled out, which fundamental principle of modern genetics would this discovery challenge the most?
Flashcards
Nettie Stevens
Nettie Stevens
US biologist who discovered sex is determined by chromosomes.
Early 20th-century Beliefs on Sex Determination
Early 20th-century Beliefs on Sex Determination
Believed sex was determined by external factors.
Stevens' Conclusion
Stevens' Conclusion
Chromosomes determining sex.
X and Y chromosomes
X and Y chromosomes
Signup and view all the flashcards
Sex Determination
Sex Determination
Signup and view all the flashcards
Mealworm Study
Mealworm Study
Signup and view all the flashcards
Chromosomal inheritance
Chromosomal inheritance
Signup and view all the flashcards
Stevens's Method
Stevens's Method
Signup and view all the flashcards
Study Notes
- Nettie Stevens was a pioneering US biologist in the early 20th century.
- Stevens discovered that an animal’s sex is determined by particular chromosomes.
- She was among the first female scientists recognized for her genetics contribution.
- Stevens' work was largely overshadowed during her lifetime.
University Career
- Nettie Stevens graduated from Stanford University with a master's in biology in 1900.
- She earned a doctorate at Bryn Mawr College in 1903.
- Her scientific career began at age 39.
- Stevens is credited with a vital breakthrough in early genetics.
- She enrolled to study biology at Stanford University in 1896 after a teaching career.
- Stevens gained a PhD from Bryn Mawr in 1903 under geneticist Thomas Hunt Morgan.
Sex Determination
- In the early 20th century, how biological sex was determined was debated.
- Many believed external factors at the embryonic stage caused it, like temperature or nutrition.
- Stevens’s research into mealworm chromosomal behavior ended this debate.
- During her study, she noted that male reproductive cells included X and Y chromosomes.
- Females produced only Xs.
- She concluded that an organism's sex is determined by inherited chromosomes from each parent.
- She published her findings in 1905.
- This research made the first link between a physical characteristic and a particular chromosome.
- Stevens’s discovery was not widely acknowledged until after her death.
Mealworm Study
- Stevens worked on chromosomal behavior in mealworms.
- This work was sponsored by the Carnegie Institute in 1904.
Major Finding
- She published her discovery of sex determination in 1905.
- This was just before US geneticist Edmund Beecher Wilson.
Untimely End
- Stevens rejected a research professor offer at Bryn Mawr due to ill health.
- She died soon after in 1912.
- Stevens carried out painstaking work studying reproductive cells under a microscope.
- She provided key data to support the theory of chromosomal inheritance.
- Her studies included many species of insects.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Nettie Stevens discovered sex is determined by chromosomes. Her university career included studies at Stanford and Bryn Mawr. Her research focused on chromosomal behavior in mealworms, and contributed to early genetics.
