Grade 10

Biology ppt
Unit 1 . Sub-fields of biology

Major discoveries that revolutionized biology

Marken Yohannes 2024 G.C
1
 Major discoveries that
revolutionized biology
Øhere are the twelve famous discoveries to
inspire you
1. Aristotle (384–322 BC)
üthe ancient Greek philosopher Aristotle was
responsible for a break through classifcation
system for living things.
üAristotle’s classifcation system was the
‘Ladder of Life’ until the nineteenth century.
For the first time, he established species
relationships and grouped them correctly
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2. Galen (129–161 AD)
ØGalen’s efforts transformed medical science.
ØGalen had a signifcant impact on the
advancement of numerous medical specialties,
including Anatomy, Pathology, Physiology,
and Neurology
ØAmong his important findings were the
distinctions between veins and arteries, as well
as the recognition that the larynx produces
voice.
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3. Antonie van Leeuwenhoek (1632–1723)
Antonie van Leeuwenhoek is well renowned for his
contributions to microscopy and how he applied it to the feld of
biology.
He invented a method for making strong lenses that, could
magnify up to 500 times. Leeuwenhoek employed microscopes
to learn more about the biological world; among his findings
were bacteria and the vacuole of the cell

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4. Carl Linnaeus (1707–1775)
Carl Linnaeus, a botanist, physician, and naturalist, devised the
method for naming, ordering, and classifying creatures that we
still use today.
His extensive collection of plant, animal, and shell specimens
inspired him to devise a system for classifying and naming
species.
He separated items into three categories – animals, plants, and
minerals – and further organized living things into classes,
orders, genera, and species. ‘Homo sapiens,’ for example -
‘homo’ is the genus and ‘sapiens’ is the species.

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5. Charles Darwin (1809–1882)
Probably the most famous naturalist of all time, Charles
Darwin’s contribution to biology and society is immense
His theory of evolution was published in On the Origin of
Species in 1859 and it caused quite the stir – he was disputing
the long-held belief that all species had been created by God at
the beginning of the world.
Evolution by natural selection combined with Mendelian
genetics is now accepted as the modern evolutionary synthesis
and forms the foundations of much biological scientifc endeavor

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6. Gregor Mendel (1822–1884)
Gregor Mendel’s extraordinary contribution didn’t get the
recognition it deserved until long afer the friar’s death.
He used peas to discover and demonstrate the laws of genetic
inheritance, coining the terms ‘dominant’ and ‘recessive’ genes
in the process.
The laws were rediscovered at the turn of the 20th century and
provided the mechanism for Darwin’s theory of natural selection
to occur.
The two theories combine to form our current understanding of
the evolutionary process

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7. Louis Pasteur (1822-1895)
Louis Pasteur is regarded as the father of medical microbiology.
His contributions to science, technology, and medicine are nearly
unparalleled in history.
He pioneered molecular asymmetry research, demonstrated that
bacteria cause fermentation and disease,
introduced pasteurization, rescued France’s beer, wine, and silk
industries, and developed anthrax and rabies vaccines

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8. Robert Koch (1843-1910)
Robert Koch was a well-known German physician who
pioneered microbiology.
As the father of modern bacteriology, he is credited
with pinpointing the precise causal agents of tuberculosis,
cholera, and anthrax, as well as providing experimental support
for the concept of infectious disease.
9. Jane Goodall (1934)
Our knowledge of wildlife and conservation has been
transformed by Jane Goodall, the UK ethologist. Best known for
her career-long studies of chimpanzees, she discovered the
animals are omnivores and tool users.

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10) Barbara McClintock (1902–1992)
American geneticist Barbara McClintock spent her career
analyzing maize, where she developed a technique for
identifying and examining chromosomes individually. Despite it
not being immediatelyrecognized, her work made it possible for
us to map human genomes.
She was awarded the Nobel Peace Prize in 1983 for her
discovery of transposition and how genes could turn their
physical characteristics on and off

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11. Watson (1928–) and Crick (1916–2004)
James Watson and Francis Crick were shot to fame in 1962 for
their discovery of the structure of DNA, winning the medical
Nobel Prize in the process.
Their model of DNA (double helix) explains how DNA
replicates, and hereditary information is coded and passed
on to descendants.

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12. Wilmut (1944) and Campbell (1954–2012)
In 1996 Ian Wilmut and Keith Campbell cloned a mammal,
famously named Dolly the Sheep.
The pair cloned Dolly using a single adult sheep cell and a
process of nuclear transfer. Dolly died afer six years but cloning
continues, although still not perfect, and certainly not ready for
human application.

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 1.4 The contributions of biological discoveries
to society and the environment
The Microscope
The microscope is a device that magnifes objects or organisms
that are too small to be seen with the naked eye.
The invention of the microscope has revolutionized the
science industry while developing other felds:
Medical feld
The use of microscopes in medicine began in the 1860s when Louis Pasteur
reported that the microscopic organisms he saw in the microscope caused
certain diseases.
Until that time, people thought diseases came from evil spirits or God.
Pasteur’s germ theory revolutionized the process of identifying, treating, and
preventing infectious diseases.

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Ecosystem study
The microscope is used to study the health of an ecosystem.
Field biologists utilize microscopes to observe a specific habitat,
such as a marine environment, by identifying the types and
numbers of microscopic organisms found in ecosystem samples.
Forensic Science
The microscope has greatly affected the feld of forensic science.
Forensics is a feld of science used to gather and analyze
evidence to establish facts that are used in a legal scenario.
The microscope is used to examine pieces of evidence collected
at a crime scene that may have information not visible to the
human eye.

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Atomic Study
The invention of the powerful atomic force (electron)
microscope has enabled scientists to study cells at an atomic
level.
Genetic Study
The microscope has had a signifcant impact on genetics
research.
A microscope is used by scientists to examine certain genetic
makeup. This also allows scientists to evaluate genetic
abnormalities, regeneration, and tissue death.
Tissue Analysis
It is common for histologists to study cells and tissues using a
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 1.5 Ethiopian biologists and their contributions
1. Professor Yalemtsehay Mekonnen
Prof. Yalemtsehay is a biologist and an academic member of
staff at the Department of Biology, Faculty of Science, Addis
Ababa University
She has worked in this department for the last 30 years. She
received her Ph.D., specializing in human physiology, from the
University of Heidelberg in Germany.
One of her research areas is the assessment of the impact of
chemical pesticide hazards on humans
The other area of her research is in the use of plants as medicine
against human and animal diseases.
She has done notable research on medicinal plants especially on
Moringa Stenopetala (shiferaw/Alekko Shekatta)
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2. Dr. Aklilu Lemma
Schistosomiasis is a common parasitic disease. It affects
200–300 million people in Africa (including Ethiopia), South
America, Asia, and parts of the Caribbean.
It is caused by parasitic flatworms which spend part of their
lifecycle in freshwater snails and part in humans.
Anyone washing, working, or playing in shallow freshwater is at
risk.
Once inside a person, the parasites mature and produce eggs
which are passed out in the urine and feces.
They also infest the blood vessels, liver, kidneys, bladder, and
other organs.

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Dr. Aklilu began his work in 1964 when he was investigating the
freshwater snails that carry the Schistosomiasis parasite around
Adwa in northern Ethiopia.
He saw women washing clothes in the water and he noticed that downstream
of the washing party there were more dead snails than anywhere else he had
collected.
The women were using the soapberry, ‘Endod’ in Amharic (Phytolacca
dodecane Dr.a), to make washing suds.
Dr. Aklilu collected some live snails from above the washing party and asked
one of the women to give him some of her Endod suds. Not long afer the suds
were put in the snail container, all the snails died.
Back in the laboratory, he showed that if the Endod berries were dried,
crushed, and diluted in water they would kill snails at very low
concentrations.
If the freshwater snails can be controlled, the spread of schistosomiasis can be
greatly reduced, Dr. Aklilu’s results were
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by Mark John in journals around the 18
 3. Professor Gebissa Ejeta
When Prof. Gebissa Ejeta was born in a small rural village his mother
was determined her son would receive a good education.
He walked 20 miles to school every sun day evening, returning home on
Friday afer a week of studying.
He specializes in plant breeding and genetics. Prof. Gebissa Ejeta did
his research on sorghum He got his Ph.D. from Purdue University in
the USA where he still holds a professorship.
He has helped to develop Africa’s frst commercial hybrid strain of sorghum
This sorghum variety not only needs less water and so is resistant to drought,
but it also yields more grain than traditional varieties.
Prof. Gebissa Ejeta developed other varieties of sorghum that are also
resistant to the parasitic Striga weed, which can destroy a big percentage
of a crop

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