Biology Theories: Epigenesis & Preformationism
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Questions and Answers

What occurs after a sperm penetrates the egg cell during external fertilization in sea urchins?

  • The sperm nucleus and egg nucleus fuse. (correct)
  • The egg immediately begins dividing.
  • The egg nucleus prevents fusion with sperm nuclei.
  • The egg allows other sperm to enter.

What did Theodor Boveri conclude from his experiments with enucleated eggs?

  • The nucleus determines the characteristics of the organism. (correct)
  • Sperm has no role in the development of an organism.
  • The characteristic of an organism is solely based on environmental factors.
  • Only the egg contributes to the hereditary material.

What was the outcome of grafting a cap from one species of Acetabularia onto the base of another species?

  • The cap develops according to the base species characteristics. (correct)
  • The cap develops characteristics of the grafted species.
  • The cap fails to regenerate at all.
  • The cap forms a completely novel structure.

What does the nucleus contain that is essential for heredity?

<p>Hereditary material. (B)</p> Signup and view all the answers

Which of the following statements about embryo development in sea urchins is true?

<p>Embryos develop with a mix of parental traits. (D)</p> Signup and view all the answers

What does the nucleus primarily control within a cell?

<p>The functions and development of the cell. (D)</p> Signup and view all the answers

What happens to an enucleated egg when sperm is introduced?

<p>It develops into the species of the sperm. (C)</p> Signup and view all the answers

What implication does the fusion of the sperm and egg nuclei have for the zygote?

<p>The zygote has unique genetic information from both parents. (C)</p> Signup and view all the answers

What is epigenesis?

<p>Process of development from seed, spore, or egg through differentiation. (B)</p> Signup and view all the answers

Who first proposed the theory of epigenesis?

<p>Aristotle (D)</p> Signup and view all the answers

What does the preformation theory suggest about the development of organisms?

<p>Every organism comes from a pre-existing miniature version, or homunculus. (C)</p> Signup and view all the answers

What significant discovery did Robert Brown make in 1831?

<p>The nucleus in plant cells. (C)</p> Signup and view all the answers

What conclusion was drawn from the fertilization studies in the 1870s?

<p>The nucleus contributes information necessary for creating a new organism. (C)</p> Signup and view all the answers

Who is known as the 'Father of Microbiology'?

<p>Antonie Van Leeuwenhoek (B)</p> Signup and view all the answers

What description fits the initial concept of a zygote?

<p>The combined sperm and egg cell that forms the first cell of a new organism. (A)</p> Signup and view all the answers

What limitation did early creationist theories impose on the scientific community?

<p>They discouraged the study of embryonic development and cell differentiation. (D)</p> Signup and view all the answers

Flashcards

External Fertilization

The process where sperm and egg cells fuse together to form a zygote, which is the first cell of a new organism.

What is the Nucleus?

The central part of a cell that contains the genetic material (DNA) which directs all the cell's activities.

Enucleated Egg

Removing the nucleus from a cell, leaving only the cytoplasm.

Boveri's Experiment

An investigation where the nucleus of one species is inserted into an enucleated egg of another species to determine the role of the nucleus in inheritance.

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Acetabularia

A large, single-celled algae that is often used in scientific studies due to its large size and distinct parts.

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Hammerling's Experiment

Hammerling's experiment involved grafting the cap of one species of Acetabularia onto the base of another species. The resulting cap always resembled the shape of the species from which the base came.

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Hereditary Material

The genetic material found within the nucleus of every cell, responsible for passing traits from parents to offspring.

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Mitosis

The process of cell division where one cell divides into two identical daughter cells, each containing a complete copy of the parent cell's genetic material.

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Meiosis

The process of cell division that produces gametes (sperm and egg cells) which have only half the number of chromosomes of a normal cell.

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Epigenesis

A theory that explains the development of organisms from a simple starting point, involving cell differentiation and organ formation. Proposed by Aristotle.

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Preformation

A theory that states organisms develop from a pre-existing, miniature version of themselves. This theory held that all life was created simultaneously.

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Antonie Van Leeuwenhoek

The first to use a powerful, single-lens microscope to observe tiny organisms, previously unseen.

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Robert Brown

A Scottish botanist who was the first to discover and name the nucleus of a cell, the cell's control center.

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Fertilization

The process where a sperm cell and an egg cell fuse to form a zygote, the first cell of a new organism.

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The Nucleus

The cell organelle that contains the genetic material (DNA) and controls the activities of the cell.

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Zygote

The initial stage of development after fertilization, where one cell contains all the necessary information to grow into a complete organism.

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The Nucleus's contribution to development

The key role of the nucleus in creating a new life. The nucleus, containing the parent's genetic information, is the key contributor to the growth and development of a new organism.

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Study Notes

Epigenesis

  • Describes the development of plants, fungi, and animals from a seed, spore, or egg through a series of steps where cells differentiate to form organs

  • Proposed by Aristotle (384-322 BC)

    • Creationist theories hinder acceptance of scientific explanations regarding the origins and development of life. These theories often conflict with empirical evidence and can foster a reluctance to embrace evolutionary biology and other scientific findings that contradict traditional creation narratives.

Preformationism

  • Theory suggesting an embryo develops from a complete miniature version of the mature organism
  • All organisms were created simultaneously
  • Succeeding generations develop from homunculi (miniature humans) or animalcules
  • Homunculi had their own sperm for reproduction
  • Explained conception as the incubator role of the woman and seed of the man.
  • The role of the mother was questioned in how offspring resembled the mother

Microscopy

  • 1671: Antonie van Leeuwenhoek, a Dutch draper, invented simple microscopes for cloth inspection
  • Used single lenses for superior magnification (270X)
  • Discovered microscopic organisms (animalcules) – "Father of Microbiology"

Discovery of the Nucleus

  • 1831: Robert Brown, a Scottish botanist, discovered the nucleus in plant cells
  • Improved lenses facilitated observation
  • Called it "Nucleus" (Latin for "little nut")

The Nucleus - Discovery of Function

  • Fertilization studies (1870s):
    • Sperm + egg = zygote (first cell of the new organism)
    • Sperm contains a nucleus (and little cytoplasm)
    • Nucleus was determined to be important in development
  • Theodor Boveri (1889):
    • Sea urchins - external fertilization and development
    • Enucleated eggs (nucleus removed)
    • Sperm from a different species added
    • Conclusion: The nucleus determines organism's characteristics
  • Joachim Hammerling (1943):
    • Acetabularia - large unicellular algae (2-5 cm tall)
    • Consist of cap, stalk, and base; nucleus in base
    • Removed the cap: base regenerated a new cap that matched species of the initial base
    • Nucleus controls development

Fertilisation

  • Oscar Hertwig (1875):
    • Sea urchins – external fertilization & development
    • Observed sperm penetrating the egg cell
    • Sperm & Egg nuclei fuse soon after
    • Embryo develops into an individual with parental traits
    • Nuclei of both egg & sperm carry hereditary material.

Summary

  • Nucleus controls cell functions and development
  • Sperm and egg nuclei fuse to create a zygote
  • Hereditary material resides in the nucleus

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BIO273 Biology - History of the Nucleus PDF

Description

Explore the fascinating theories of biological development including Epigenesis and Preformationism. Learn about Aristotle's contributions to life origins and the advancements made by Antonie van Leeuwenhoek in microscopy. This quiz delves into the historical context and significance of these scientific ideas.

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