This document provides an overview of the major branches of life science. It discusses 14 branches: ecology, botany, zoology, entomology, microbiology, cell biology, paleontology, genetics, and physiology. Ecology examines interactions between organisms and their environment. Botany focuses on plants, zoology on animals, and entomology on insects and related groups. Microbiology looks at microorganisms like bacteria and viruses. Cell biology studies processes within individual cells. Paleontology studies extinct organisms through fossils. Genetics examines inheritance of traits. Physiology focuses on chemical processes that support life.

1. Life Science
GRADE 7

2. What is Life Science
 Life science is an enormous field of study that examines every living
thing on earth. From bacteria to begonias to beluga whales, life
sciences aim to learn everything about life on this planet.

3. What is Life Science
 As the name might suggest, life science studies life in all its forms,
past and present. This can include plants, animals, viruses and
bacteria, single-celled organisms, and even cells. Life sciences study
the biology of how these organisms live, which is why you may hear
this group of specialties referred to as biology.

4.  As you might expect, with an estimated 8.7 million species of
animals, about 400,000 species of plants, and countless species of bacteria
and viruses, there are a lot of different forms of life you can study. Many
life science researchers specialize in one class or organism, and some
specialties such as zoology have even more subspecialties. There are more
than thirty different branches of life sciences, but we’ll review some of the
major branches here.

5. Ecology
 Ecology looks at the interactions between organisms and their
environment. This can include topics like the food chain, parasitic and
beneficial relationships, and relationships within species. Ecology also
examines things like biodiversity, organism population numbers, and
distribution of those organisms.
 In effect, ecology aims to get an overall picture of the way ecosystems
work. These systems are complex, dynamic webs of life that are constantly
shifting and maintaining a delicate balance without which the system
would collapse. This ecosystem could be as large as an entire rainforest or
as small as a pond in Minnesota.
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7. Botany
 Botany studies is a branch of biology (pun intended) that looks at plants.
Everything from lichens, grass, and other groundcovers to the towering
redwoods fall under the realm of botany. It may also include fungi and
algae, which differ from other varieties of plants.
 Botany is one of those subclasses of biology that has subdivisions of its
own. Some scientists focus on plant biochemistry, while others look at
plant ecology, a branch that sits somewhere between botany and ecology.
Additional subdivisions include plant genetics, evolution, physiology, and
anatomy and morphology.
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9. Zoology
 Whereas botany focuses on the plant kingdom, zoology looks at the
animal kingdom. It looks at characteristics of different animals, including
their behavior, breeding, migration patterns, habitats, and more. It also
works to identify new species; of the estimated 8.7 million animal species
on earth, we only know about 1.2 million species.
 As with ecology and botany, zoology crosses over with several other
disciplines, including paleontology, entomology, and genetics. Different
zoologists focus on different types of animals, including birds, reptiles,
mammals, fish, and more. There are more than a half-dozen subfields of
zoology.

11. Entomology
 Entomology is the study of all the creepy crawly things in the world. This
field officially studies insects, but it may also examine arachnids,
myriapods, worms, snails, and slugs. This could be considered a branch of
zoology since insects technically fall within the animal kingdom.
 Of the 1.2 million species we know about, insects account for nearly
900,000 species. They date back at least 400 million years (far older than
the oldest dinosaurs) and are found in nearly every ecosystem on Earth.
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13. Microbiology
 Microbiology looks at some of the smallest of all living beings – single-
celled organisms or small cell colonies. This can include bacteria, viruses,
parasites, and other tiny organisms that live all around and inside us.
Historically, microbiology has been one of the hardest fields to pin down
because getting a clear image of the subjects has been so hard.
 For example, viruses have both fallen under and been expelled from the
field of microbiology. It’s hard to nail down a specific definition of life, and
viruses are one of those things that like to play jump rope with that line.
And that’s to say nothing of the 99 percent of microorganisms that can’t be
observed using traditional methods.

15. Cell Biology
 Cell biology goes yet smaller than microbiology, taking a look at the living
systems that exist within individual cells. That’s right; even the cells that
make up your body have their own tiny ecosystems. Remember learning in
ninth-grade biology that the mitochondria is the powerhouse of the cell?
 Cell biology looks at the life processes of individual cells, including
metabolic processes, reproduction, signaling pathways, and the chemical
composition of the cell. This gives us a better idea of how life on a larger
scale works. It’s especially important in fields like genetics and
pharmacology.
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17. Paleontology
 Paleontology looks at life that isn’t, well, alive anymore. Specifically, it
studies dinosaurs and how they may have lived. It is based around the
fossil record and the clues we can glean from those preserved remains.
 Paleontology is somewhat on the outskirts of biology, bumping up against
geology. But while it does include a close study of different rocks,
paleontology aims to use those rocks as a way to reconstruct a record of
life that once existed on this planet. Paleontologists try to use dinosaur
fossils to reverse-engineer how they lived, what they looked like, and even
how they died.
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19. Genetics
 Although the study of DNA and the genome is relatively new, genetics is a
field that traces all the way back to Gregor Mendel and his pea plants. It
looks at how traits are passed down and how they adapt to suit the
environment. Only in recent years have we come to understand exactly
how that genetic inheritance happens.
 With the discovery of DNA, genetics has expanded to include traits that we
only believe may be genetically linked. Geneticists are writing life science
articles exploring whether traits like addiction, cancer, talent, and other
such things may be passed down genetically and how. In the future, we
may even see genetic modifications that could prevent cancer.
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21. Physiology
 Whereas botany and zoology look at organisms as being within their environments,
physiology focuses on how those beings stay alive. This includes organ systems, organs,
cells, and molecules that run the chemical processes that support life. Physiology sees
you not as a person interacting with the world around you or with a complex mental life,
but as an intricate dance of chemical interactions that work to keep you alive.
 Physiology can look at any of the forms of life we’ve discussed. Plant, animal, human,
cellular, and microbial physiology are all subsets of this field of study. Physiology is also
intimately tied to epidemiology and pharmacology.
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