Ace Your Biology Exam: Long Questions-Answers for Class 9 board exams on 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." |
| 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.
Biology Definition
The branch of science that deals with the scientific study of living organisms, such as plants, animals & microorganisms is called biology.
Explanation
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.
Characteristics of organisms of five kingdom system
All living things are classified into five kingdoms (the biggest
unit of classification). This system of classification was presented by Robert
Whittaker in 1968. Following are the characteristics of organisms of each
kingdom
a. Kingdom Monera or Kingdom Prokaryotae
Organisms of Kingdom Monera have the following general characteristics- 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).
b. Kingdom Protista or Kingdom Prototista
Organisms of Kingdom Protista have the following general characteristics
- 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.
c. Kingdom Fungi
Organisms of Kingdom Fungi have the following general characteristics
- They are mostly multicellular eukaryotes organisms.
- They lack chlorophyll so are not autotrophs but heterotrophs.
- Being heterotrophs they live as
- Saprophytes mean they obtain their food from dead organic matter, or
- Parasites mean that they obtain their food from living organisms called hosts and cause diseases in them.
- They do not move about.
Examples are Breadmold, Mushrooms, Rust, and Smut fungi.
d. Kingdom Plantae
Organisms of Kingdom Plantae have the following general characteristics.
- This kingdom includes only plants of different types.
- They contain chlorophyll so can prepare their food (autotrophs) by the process called Photosynthesis (photo = light, synthesis = preparing).
- 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.
e. Kingdom Animalia
Organisms of Kingdom Animalia have the following general characteristics.
- 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 in their backbone are called vertebrates e.g. man, snake, cat, etc.
- Invertebrates: Those animals which don’t have a vertebral column in their backbone are called invertebrates e.g. earthworms, starfish, etc.
Enlist the various levels of biological organization and explain it with an example.
Levels of biological organization
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. The following discussion summarizes each level with examples
Level 1: Sub-atomic particles and atoms
Every living and non-living matter is made up of small and simple units called atoms. Each atom is then composed of electrons, protons, and neutrons (called sub-atomic particles). From the combination of atoms, elements are formed. There are approximately 118 elements discovered yet, and only 16 elements combine to form the body mass of living things. Out of 16 elements, only 6 elements i.e. O, C, H, N, Ca, P make 99% of protoplasm. While the remaining 10 elements i.e. K, S, Cl, Na, Mg, Fe, Cu, Mn, Zn, and I collectively make up 1% of protoplasm. These 16 elements are called bio-elements.
Level 2: Molecules and compounds
Atoms combine through attractive forces (bonds) and form molecules and compounds. Similarly, these 16 bio-elements combine to form bio-molecules. They may be
- Micro bio-molecules: Those having low molecular weight, such as glucose, amino acids, water, etc. and
- Macro bio-molecules: Those having higher molecular weight e.g. starch, proteins, lipids, etc.
Level 3: Organelles
When bio-molecules combine in a systematic way they form
sub-cellular structures called organelles. These organelles are the main
components of our cells. For example, mitochondrion is an organelle
that is known as power-house of the cell. Similarly, ribosomes,
chloroplast, endoplasmic reticulum, etc. are organelles.
Level 4: Cells
By the combination of organelles cells (the basic unit of
life) are formed. All organisms are made up of one cell (unicellular
organisms) or more than one cell (multicellular organisms).
Level 5: Tissues
A group of similar cells, which perform a particular function in the body is called tissue.
Tissues
are formed by the combination of cells that perform similar functions. For
example
- Plant tissues e.g. mesophyll tissue is made of cells that perform photosynthesis.
- Similarly animal tissues e.g. cardiac tissues are made up of cells that causes heart to beat.
Level 6: Organs
When a group of tissues combines with each other they form
organs. For example, stomach is an organ that is made of two types of
tissues i.e. epithelial tissues and muscular tissues.
Level 7: Organ systems
By connection of organs with each other, the organ system is
formed. For example, the circulatory system is an organ system that is
formed by the combination of organs such as the heart, arteries, veins, and capillaries.
Level 8: Organism
At this final stage, an organism is formed by the combination of an organ system. For example, man (human) is an organism made up of a circulatory system, digestive system, nervous system, reproductive system, etc. similarly, in plants root and shoot system form the plant body.
Describe levels higher than the organism level.
Following are the levels higher than the organism level in levels of biological organization.
a. Species
A group of similar organisms that can freely interbreed with one another to produce fertile offspring is called a specie.
For example, Humans, Gorillas, Lizards, crocodiles, Horses, Lions, etc. are some examples of species.
b. Population
Organisms of the same species living together in the same area form population of that species.
For example, the Human population, bee population, rats population, etc.
c. Community
Members of different species living together in the same area form a community. For example, desert communities consist of lizards, snakes, birds, mice, rabbits, etc.
d. Ecosystem
An area of nature where living organisms interact with each other and also with their non-living environment is called an ecosystem.
For example, forest ecosystems, desert ecosystems, ocean (marine) ecosystems, etc.
e. Biosphere
The region of the surface and atmosphere of the earth occupied by living organisms is called the biosphere.
As the name suggests that biosphere is the sum (total) area needed for biological activities. For better understanding, the biosphere is divided into
- Lithosphere: The solid portion of the earth's surface is called the lithosphere.
- Hydrosphere: The portion of earth contained by water is called the hydrosphere.
- Atmosphere: The mass of air around the earth is called the atmosphere.
Discuss the various cellular organization.
Cellular organization
All living organisms are made up of one or more cells. On the basis of the number of cells, organisms can be categorized into the following three types
I. Unicellular organization
Those living organisms which are made up of only one cell are called unicellular organisms.
For example, Amoeba, Euglena, Paramecium, Chlamydomonas, etc. are unicellular organisms. These organisms can perform all vital activities such as respiration, digestion, excretion, reproduction, etc. Unicellular organisms live independently.
II. Colonial organization
The type of cellular organization in which many unicellular organisms live together in the form of a colony is called colonial organization.
For example, Volvox (green algae) live in a colony known as the coenobium colony which consists of 500-60,000 pear-shaped cells. Vegetative cells are concerned with nutrition and locomotion. Volvox is found in temporary and permanent water-containing areas. Volvox can reproduce both sexually (occurs by sperms and eggs) and asexually.
III. Multicellular organization
Those organisms which are made up of more than one cell are called multicellular organisms.
For example, humans, mustard plants, frogs, lizards, snakes, etc. are multicellular organisms. We will explore multicellular organization by taking examples of plants (Mustard plants) and animals (frogs).
a. Mustard plant
- The botanical name of a mustard plant: is Brassica campestriss
- Parts of Mustard plant body
The plant body is divided into the following two parts
- Vegetative part: It consists of roots, stems, branches, and leaves.
- Reproductive part: It consists of only flowers.
b. Frog
- Zoological name: Rana
Tigrina
- Parts of frog body: The body of a frog consists of a well-developed organ system that works together in close coordination. In such coordination, each part of its body performs a specific job. For example
- The circulatory system works with the digestive system.
- The nervous system works with the muscular system.
- The respiratory system works with the circulatory system.
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