This document discusses biology and its branches. It defines biology as the study of life and outlines many sub-disciplines within biology including botany, zoology, anatomy, and ecology. It also describes the basic units of life like cells, atoms, and biomolecules. Specifically, it contrasts the key differences between plant and animal cells like plant cells having cell walls and chloroplasts while animal cells do not.

1. Biological Science
NSC 2

2. Branches of Science

3. Main Branches
 Natural Science
 Social Science
 Formal Science
 Applied Science

4. What is Science???
 Science is the pursuit and application of
knowledge and understanding of the
natural and social world following a
systematic methodology based on
evidence.

5. Biology
 Bio means “life” and logos means “study”
 Biology- study of life or living matter and its forms, origin, growth,
reproduction, structure and behavior

6. Branches of Biology
 Botany is the study of plants.
 Zoology is the study of animals.
 Anatomy is the study of internal structures of living things.
 Biochemistry is the use of chemistry in the study of living things.
 Ecology is the study of the relationships of living things to each other and to
their environment.
 Pathology is the study if diseases, generally in animals. Phytopathology is the
study of diseases in plants.
 Physiology is the study of normal functions of living things.

7.  Taxonomy is the classification and naming of living things.
 Genetics is the science of heredity and the lifelong development of living
things
 Embryology is the study of the formation and development of living things
from fertilization to birth as independent organisms.
 Pharmacology is the study of the actions of chemicals on and in living things.
 Endocrinology is the study of hormones and their actions.
 Cytology is the study of cells.
 Histology is the study of tissues.

8.  Bacteriology is the study of bacteria.
 Virology is the study of viruses.
 Mammalogy is the study of mammals.
 Ornithology is the study of birds.
 Herpetology is the study of reptiles and amphibians,
 Ichthyology is the study of fishes.
 Entomology is the study of insects.
 Helminthology is the study of worms.
 Microbiology is the study of microorganisms.
 Mycology is the study of fungi.
 Paleontology is the study of fossils.

9. What is Life???
 A condition that shows distinction of plants and animals from inorganic
matters.

10. Atom
 The basic structure of matter

11. Biomolecules
 Biomolecules are molecules that occur naturally in living organisms.
 Biomolecules include macromolecules like proteins, carbohydrates, lipids and
nucleic acids.

12. Four Major Classes of Biomolecules
• There are four major classes of biomolecules:
• Carbohydrates
• Lipids
• Proteins
• Nucleic acids

13. Functions of Biomolecules
 Carbohydrates provide the body with source of fuel and energy, it aids in proper
functioning of our brain, heart and nervous, digestive and immune system.
Deficiency of carbohydrates in the diet causes fatigue, poor mental function.
Each protein in the body has specific functions, some proteins provide structural
support, help in body movement, and also defense against germs and infections.
Proteins can be antibodies, hormonal, enzymes and contractile proteins.
Lipids, the primary purpose of lipids in body is energy storage. Structural
membranes are composed of lipids which forms a barrier and controls flow of
material in and out of the cell. Lipid hormones, like sterols, help in mediating
communication between cells.
Nucleic Acids are the DNA and RNA, they carry genetic information in the cell.
They also help in synthesis of proteins, through the process of translation and
transcription.

14. In 1665
Robert Hooke
 Hooke looked at the bark
of a cork tree and
observed its microscopic
structure. In doing so, he
discovered and named the
cell – the building block of
life.
 He thought the objects he
had discovered looked like
the individual rooms in a
monastery, which were
known as cells.

15. Animal cell
 All animals are multicellular. Human body
contains trillions of cells.
 All animal cells are eukaryotic, they are
surrounded by cell membrane and do not have a
cell wall.

17. Plant cell
 Plant cell are eukaryotic cells, they are
membrane bound organelles. They are surrounded
by a rigid cell wall.
 Plant cells are similar to animal cells in being
eukaryotic and they have similar cell organelles.
 Generally, plant cells are larger than animal cells
and are mostly similar in size and are rectangular
or cube shaped.
 plant cell contains a few distinctive features like
a cell wall, large vacuole and plastids.

19. Plant Cell Animal Cell
Cell Wall
Cell wall made of cellulose is present in
almost all cells.
Cell wall is absent.
Plastids
Plastids like leucoplasts, chloroplast
and chromoplasts are present.
No plastids found.
Chloroplasts
Plants cells have chloroplasts to
prepare their own food.
Chloroplasts completely absent.
Vacuoles
Cell sap containing vacuoles are
present.
Vacuoles are usually absent or one
or more small vacuoles are seen.
Lysosomes Lysosomes not evident. Lysosomes occur in cytoplasm.
Nucleus
Due to the presence of the vacoule
at the centre of the cell, nucleus
may be located at the edge of the
cell.
Nucleus is usually located centrally.
Golgi bodies
Plant cells have many simpler units
of golgi complex, called dictyosomes.
Animal cells have a single highly
elaborate golgi complex.
Endoplasmic reticulum Present Present
Ribosomes Present Present
Mitochondria Present Present
Centrioles Present only in lower plant forms. Present