Text C Biology 7.1 Life From Life

Question 1

What is the theory of spontaneous generation?

Answer 1

The theory that some organisms arise from non-living matter, such as maggots from rotting meat.

Also known as abiogenesis, this theory was widely accepted for over 2000 years.

Question 2

Who was the first person to use scientific experiments to test the theory of spontaneous generation?

Answer 2

Francesco Redi

An Italian physician who lived from 1626 to 1697.

Question 3

What hypothesis did Redi propose regarding maggots on rotting meat?

Answer 3

Maggots hatched from objects dropped by flies on the meat.

Redi observed flies depositing eggs on the meat, leading to his hypothesis.

Question 4

Describe the setup of Redi’s controlled experiment.

Answer 4

Redi placed pieces of meat in two jars: one covered with cloth and one open to flies.

The cloth allowed air to enter but prevented flies from accessing the meat.

Question 5

What were the results of Redi’s experiment?

Answer 5

Maggots appeared in the open jar but not in the cloth-covered jar.

This indicated that maggots did not arise from spontaneous generation.

Question 6

What conclusion did Redi reach from his experiment?

Answer 6

Maggots found in rotting meat were not produced by spontaneous generation.

Redi’s experiment was a pivotal moment in disproving spontaneous generation.

Question 7

What renewed the debate over spontaneous generation after Redi’s experiments?

Answer 7

The discovery of microscopic single-celled organisms.

Some scientists argued that these microorganisms were evidence of spontaneous generation.

Question 8

What did some scientists believe about microorganisms and spontaneous generation?

Answer 8

They believed an ‘active principle’ in the air created the microorganisms.

This belief persisted for another 200 years following Redi’s experiments.

Question 9

True or False: Aristotle conducted experiments to test his hypothesis on spontaneous generation.

Answer 9

False

Aristotle based his beliefs on observations but did not test them scientifically.

Question 10

Fill in the blank: The theory of spontaneous generation was widely accepted for over _______ years.

Answer 10

2000

This long-standing belief was eventually challenged by scientific experiments.

Question 11

What is the purpose of a control group in an experiment?

Answer 11

To provide a baseline for comparison with the experimental group

The control group is not exposed to the experimental treatment.

Question 12

What is an experimental group?

Answer 12

The group that receives the treatment or condition being tested

This group is compared against the control group.

Question 13

Who conducted an experiment with meat in jars to study spontaneous generation?

Answer 13

Francesco Pedi

He left one jar open and covered the other with cloth.

Question 14

What did Pasteur conclude from his experiments regarding spontaneous generation?

Answer 14

Spontaneous generation did not occur

Pasteur’s work supported the theory of biogenesis.

Question 15

What is fermentation?

Answer 15

The biochemical process that converts sugars into acids, gases, or alcohol

Examples include souring milk, and converting grape juice into wine.

Question 16

What was Pasteur’s hypothesis about the ‘active principle’ in air?

Answer 16

That it was also an organism

This led to his experiments with swan-neck flasks.

Question 17

Describe the design of Pasteur’s swan-neck flask.

Answer 17

A glass flask with a long, S-shaped neck

This design allowed air in but prevented microbes from reaching the broth.

Question 18

What was the outcome of Pasteur’s swan-neck flask experiment?

Answer 18

The broth remained clear, indicating no microbial growth

Micro-organisms settled in the neck and did not contaminate the broth.

Question 19

What happens when the broth in Pasteur’s flask is tilted?

Answer 19

The broth becomes clouded with micro-organisms

This indicates that the microbes from the neck can contaminate the broth.

Question 20

What did Pasteur observe when he purposely placed micro-organisms in nutrient broth?

Answer 20

The micro-organisms multiplied

This was akin to planting seeds.

Question 21

What theory did Rudolf Virchow propose in 1858?

Answer 21

Biogenesis

This theory states that living organisms arise only from other living organisms.

Generated by life

Question 22

What did Pasteur’s experiments provide evidence for?

Answer 22

The theory of biogenesis

His results supported the idea that life comes from life.

Question 23

What is pasteurization?

Answer 23

The process of heating food to kill unwanted bacteria

Named after Louis Pasteur, it is used to improve food safety.

Question 24

What invention allowed scientists to observe objects in greater detail?

Answer 24

The invention of microscopes

Microscopes made it possible to magnify objects and observe them closely.

Question 25

What are the smallest functional units of life?

Answer 25

Cells ## Footnote All living things are composed of cells.

Question 26

In which century were cork cells first observed?

Answer 26

Mid-1600s ## Footnote Cork cells were among the first cells observed using microscopes.

Question 27

What significant structures were described by scientists in the 1830s?

Answer 27

* The nucleus of the plant cell (1831) * The cytoplasm (1836) ## Footnote These observations were crucial for understanding cell structure.

Question 28

What conclusion did researchers reach about animals in 1839?

Answer 28

All animals are made of cells ## Footnote This conclusion was drawn from microscopic examination of animal tissues.

Question 29

True or False: Early users of microscopes were able to see detailed structures of cells.

Answer 29

False ## Footnote Early observations were basic and lacked the detail that modern science provides.

Question 30

Fill in the blank: By the 1670s, scientists were able to describe _______ organisms.

Answer 30

pond-water ## Footnote These observations contributed to the understanding of microscopic life.

Question 31

What was a limitation of the first researchers who observed cells?

Answer 31

They had little concept of what they were seeing ## Footnote Many did not realize the groundbreaking nature of their discoveries.

Question 32

How did the information provided by early micrographs change over time?

Answer 32

It evolved to show more detail and understanding of microscopic structures ## Footnote Early micrographs revealed basic structures, which improved with advancements in microscopy.

Question 33

Who was the English scientist that discovered cells in cork?

Answer 33

Robert Hooke

Question 34

What did Robert Hooke name the structures he observed in cork?

Answer 34

Cells

Question 35

What type of microscope did Robert Hooke use to make his discovery?

Answer 35

Crude compound light microscope

Question 36

What was the magnification of Hooke's microscope?

Answer 36

About 30x

Question 37

What did Hooke believe the cork structures resembled?

Answer 37

Monks' small rooms or cells in a monastery

Question 38

In what year did Robert Hooke publish his findings in Micrographia?

Answer 38

1665

Question 39

Who was the first person to describe single-celled microorganisms?

Answer 39

Antony van Leeuwenhoek

Question 40

What year did van Leeuwenhoek make his discoveries?

Answer 40

1674

Question 41

What was Antony van Leeuwenhoek's profession?

Answer 41

Dutch linen merchant

Question 42

What type of microscope did van Leeuwenhoek build?

Answer 42

Single-lens microscope

Question 43

What was the maximum magnification of van Leeuwenhoek's lenses?

Answer 43

Up to 500x

Question 44

What term did van Leeuwenhoek use to describe the tiny organisms he observed?

Answer 44

Animalcules

Question 45

What kinds of specimens did van Leeuwenhoek study?

Answer 45

Blood cells, pond-water organisms, matter scraped from his teeth

Question 46

What did van Leeuwenhoek write about the matter scraped from his teeth?

Answer 46

There were many very little living animalcules, very prettily a-moving

Question 47

In which scholarly journal were van Leeuwenhoek's letters printed?

Answer 47

Philosophical Transactions of the Royal Society of London

Question 48

What significant role did the invention of the microscope play in scientific discovery?

Answer 48

Helped scientists to overcome limits to their understanding

Question 49

True or False: Hooke realized the significance of his discovery of cells.

Answer 49

False

Question 50

Fill in the blank: The discovery of cells helped scientists understand the _______ of organisms.

Answer 50

Functioning

Question 51

What did the process of collecting evidence about cells lead to?

Answer 51

The development of the cell theory

Question 52

How did scientists communicate their findings about cells?

Answer 52

By publishing their observations and findings

Question 53

What is the main impact of new technologies, like the microscope, on cell biology?

Answer 53

Expanded and revised explanations of cells

Question 54

Who were the two German scientists that contributed to the development of cell theory?

Answer 54

Matthias Jakob Schleiden and Theodor Schwann

Question 55

What conclusion did Schleiden reach about plants?

Answer 55

All plants are composed of cells and the materials produced by cells

Question 56

What did Schleiden consistently observe in very young cells?

Answer 56

Nuclei

Question 57

What hypothesis did Schwann develop based on his observations?

Answer 57

Animal tissues contain cells

Question 58

What is the first principle of the cell theory as stated by Schwann?

Answer 58

All organisms are composed of one or more cells

Question 59

What did other scientists do in response to Schwann's claim?

Answer 59

They tested his claim and provided supporting evidence

Question 60

What misconception did Schleiden and Schwann have about cell formation?

Answer 60

Cells formed from the crystallization of non-living materials or by budding from surfaces of other cells

Question 61

Who corrected the misconceptions about cell formation?

Answer 61

Rudolf Virchow

Question 62

What did Virchow conclude about the origin of cells?

Answer 62

Cells divide to produce more cells

Question 63

What is the cell theory?

Answer 63

1. All organisms are composed of one or more cells 2. The cell is the smallest functional unit of life 3. All cells are produced from other cells

Question 64

What are some key differences among types of cells?

Answer 64

Differences among plant cells, animal cells, and single-celled organisms

Question 65

Fill in the blank: The cell is the _______ functional unit of life.

Answer 65

smallest

Question 66

True or False: Virchow supported the idea of spontaneous generation.

Answer 66

False

Question 67

What did Virchow's observations of dividing cells lead him to conclude?

Answer 67

'Where a cell exists, there must have been a pre-existing cell'

Question 68

What did the theory of biogenesis imply about the origin of cells?

Answer 68

Cells are created from pre-existing cells, not through spontaneous generation

Question 69

What significant observation did Schwann make regarding animal tissues?

Answer 69

Animal tissues did not closely resemble plant cells

Question 70

Fill in the blank: _______ was a supporter of the theory of biogenesis.

Answer 70

Rudolf Virchow