Ace Your Biology Exam: Long Questions-Answers for Class 9 Board Exams
Chapter 1: "Introduction to Biology"
Welcome to the Ultimate Biology Guide for Class 9 Students!
This comprehensive blog post covers all the important topics related to Chapter 1 "Introduction to Biology" in the Biology Course of various boards including BISE and Federal Boards. From the definition of Biology to the Five Kingdom System of Classification, our goal is to help students understand and retain the key concepts of this chapter.
We'll cover the levels of biological organization, from the cellular level to the organism level, and even higher levels of the organization. Our focus is on providing long question-answers that are commonly asked in board exams, home exams, and entry tests. With these comprehensive notes, we aim to help students get higher marks and excel in their Biology exams.
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Class 9 Biology Long Answers Notes on Introduction to Biology
From Notes Library of H.E.S (Health, Education, and Skills)Define and explain the word biology. Also, describe its various branches.
The branch of science that deals with the scientific study of living organisms, such as plants, animals & microorganisms is called biology.
The word biology is the combination of two Greek words.
Bio: Bio means life or living things.
Logos: Logos means to study, knowledge, or thoughts.
So the word biology means the study or knowledge of living organisms, such as plants, animals, and microorganisms.
Main branches of biology
Following are the three main branches of biology:
- a. Botany (Greek word, Botanikos-Plants): The branch of biology that deals with the scientific study of plants is called botany.
- b. Zoology: The branch of biology that deals with the scientific study of animals is called zoology.
- c. Microbiology: The branch of biology that deals with the scientific study of microorganisms (viruses, Bacteria, Fungi, etc) is called microbiology.
Sub-branches of biology
Following are the sub-branches of biology, derived from the main branches:
1. Morphology (Morph means form): The branch of biology that deals with the study of forms and structures of living organisms is called morphology.
2. Anatomy (Ana=up & tomia=cutting): The branch of biology that deals with the study of the internal structures of living organisms is called anatomy or internal morphology.
3. Physiology: The branch of biology that deals with the study of the function of living organisms and their parts (organs/organelles) is called physiology.
4. Embryology (Embryo=life in egg): The branch of biology that deals with the study of developmental changes from fertilized eggs to newly born babies or seeds is called embryology.
5. Taxonomy: The branch of biology that deals with the study of naming and classification of living organisms into groups and sub-groups on the basis of similarities or differences is called taxonomy.
6. Cell biology or Cytology (cyte=cell): The branch of biology that deals with the microscopic study of cells and their organelles is called cytology.
7. Histology: The branch of biology that deals with the microscopic study of animals' and plants' tissues is called histology.
8. Paleontology (Paleous means ancient and anta means beings): The branch of biology that deals with the study of fossils (dead remains) of extinct organisms is called paleontology. While Paleobotany is the study of plants fossils, and Paleozoology is the study of animal fossils.
9. Immunology: The branch of biology that deals with the study of body resistance against disease-causing organisms (i.e. immunity) is called immunology.
10. Entomology (Entomon, a Greek word, that means notched and refers to a segmented body of the insect): The branch of biology that deals with the study of insects is called entomology.
11. Genetics: The branch of biology that deals with the study of the transmission of hereditary characters from parents to offspring is called genetics.
12. Biotechnology: The branch of biology that deals with the study of applications of living organisms for the welfare of human beings is called biotechnology. For example, the use of yeast, synthesis of drugs, antibiotics, medicines, and preservation of food.
13. Environmental biology or Ecology: The branch of biology that deals with the study of the inter-relationship of organisms with their environment is called ecology.
14. Parasitology: The branch of biology that deals with the study of parasitic organisms is called parasites. (Those organisms that get benefits from their hosts and also cause diseases in them are called parasites.)
15. Social biology: The branch of biology that deals with the study of social animals such as bees, ants, flocking birds, humans, etc. is called social biology.
16. Pharmacology (Pharmakon means drugs): The branch of biology that deals with the study of the uses, effects, and actions of drugs is called pharmacology.
17. Microbiology: The branch of biology that deals with the study of microorganisms such as viruses, bacteria, etc. is called microbiology.
Briefly discuss the five kingdom systems. Elaborate on each kingdom briefly with the living organisms included in it.
All living things are classified into five kingdoms (the biggest unit of classification). This system of classification was presented by Robert Whittaker in 1968.
They are unicellular simplest organisms. Their cell wall is made up of murein and has no nuclear membrane. They are called Prokaryotes means that as they have no nuclear membrane so they lack an organized nucleus. Moneras can be found in the oldest fossils bearing rocks. They also don’t have membrane-bound cytoplasmic organelles. Examples are Bacteria and Blue-green algae (Cyanobacteria).
These organisms are more complex than Monera. They are Eukaryotes means that they have an organized nucleus as well as membrane-bounded cytoplasmic organelles. They may be unicellular or multicellular. Some protists have chlorophyll so can make their food (autotrophs) while others don’t have chlorophyll so can’t make their own food (heterotrophs). Examples are Protozoan, Euglena, Chlamydomonas, Yeast, etc.
They are mostly multicellular eukaryotes organisms. They lack chlorophyll so are not autotrophs but heterotrophs. Being heterotrophs they live as Saprophytes (obtain food from dead organic matter), or Parasites (obtain food from living hosts). They do not move about. Examples are Breadmold, Mushrooms, Rust, and Smut fungi.
This kingdom includes only plants of different types. They contain chlorophyll so can prepare their food (autotrophs) by the process called Photosynthesis. Their cell wall is made up of cellulose. They are multicellular. They have well-developed vegetative bodies and can reproduce. Examples are Rose, Pinus, Mango plant, etc.
They are all multicellular organisms. They are eukaryotes. They don’t have chlorophyll so can’t prepare their food and are so heterotrophs. Animals can broadly be divided into:
• Vertebrates: Those animals which have a vertebral column (man, snake, cat).
• Invertebrates: Those animals which don’t have a vertebral column (earthworms, starfish).
Enlist the various levels of biological organization and explain it with an example.
Bodies of living organisms are made up of different parts organized in a certain manner. These parts of the organized pattern are called levels of biological organization.
Level 1: Sub-atomic particles and atoms
Every living and non-living matter is made up of atoms. Each atom is composed of electrons, protons, and neutrons (sub-atomic particles). Out of 118 elements, 16 are bio-elements. 6 elements (O, C, H, N, Ca, P) make 99% of protoplasm. The remaining 10 (K, S, Cl, Na, Mg, Fe, Cu, Mn, Zn, I) make up 1%.
Level 2: Molecules and compounds
Bio-elements combine to form bio-molecules. They are categorized as Micro bio-molecules (low weight like glucose, water) and Macro bio-molecules (higher weight like starch, proteins).
Level 3: Organelles
Bio-molecules form organelles. For example, mitochondrion is the "power-house of the cell." Other examples include ribosomes and chloroplasts.
Level 4: Cells
By the combination of organelles, cells (the basic unit of life) are formed. Organisms can be unicellular or multicellular.
Level 5: Tissues
A group of similar cells performing a particular function. Examples: Mesophyll tissue in plants (photosynthesis) and Cardiac tissue in animals (heart beat).
Level 6: Organs
Tissues combine to form organs. For example, the stomach is an organ made of epithelial and muscular tissues.
Level 7: Organ systems
Organs connect to form systems. For example, the circulatory system includes the heart, arteries, veins, and capillaries.
Level 8: Organism
The final stage formed by organ systems. For example, a human is an organism made up of circulatory, digestive, and nervous systems.
Describe levels higher than the organism level.
a. Species: A group of similar organisms that can freely interbreed to produce fertile offspring. Examples: Humans, Gorillas, Lions.
b. Population: Organisms of the same species living together in the same area. Example: Human population, bee population.
c. Community: Members of different species living together in the same area. Example: Desert community (lizards, snakes, birds).
d. Ecosystem: Area where living organisms interact with each other and their non-living environment. Example: Forest or marine ecosystems.
e. Biosphere: The region of the surface and atmosphere of the earth occupied by living organisms. It is divided into:
• Lithosphere: Solid portion of the earth.
• Hydrosphere: Water portion of the earth.
• Atmosphere: Mass of air around the earth.
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