أوراق عمل مراجعة Cells and Life العلوم منهج انجليزي الصف السادس
Lesson 1: Cells and Life
Revision Notes
Key Words
Cells — basic functioning unit of living things
— a device used to magnify (make bigger) any (object under observation)
Magnification — the number of times the object gets bigger under the (e.g. 1000x means the object gets bigger times)
Light microscope that uses light to see the specimen and has a lower magnification
Electron microscope — a that uses beam of electrons and has a higher magnification
Living things — include all forms of bacteria, fungi, protists, plants, and animals and have characteristiß of life (MRSGREN)
Hierarchy — arrangement from simple to complex
Unicellular — made up of one cell
Multicellular — made up of many cells
. Prokaryotic — cell without the nucleus and the genetic information (DNA) is freely floating on the cytoplasm
. Eukaryotic — cell where the DNA or the genetic formation is within the nucleus
. Homeostasis — ability to maintain constant body
. Stimuli — anything that causes a response
. Extemal stimulu/ stimuli — changes that outside the tXdy and is passes. to us through our sense organs (eyes, nose, ears, tongue, skin) e.g. levels of sunlight
. Internal stimuli — any change that happens within the body e.g changes in blood sugar levels
CHARACTERISTICS OF LIVING THINGS
For a living thing to be called living thing, it must possess ærtain characteristics
• Such characteristics are
Movement
Respiration
Sensitivity
Homeostasis
Growth & Reprcxiuction
Excretion
Nutrition
1. Living things are organized
Living things are organized from simple to complex
Organization starts frorn cells* tissues* organs* organ systems organism
2. Living things grow and develop
Living things grow and develop
• Growth refers to the increase in size
Development refers to the growth in mental and other skills
3. Living things
Reprcxiuction is the ability to make offsprings similar to the parents
• It can sexual and asexual reproduction
4. Living things to stimuli
Stimuli are changes that happen either inside or outside the bcxiy that the living things have to respond to
Internal stimuli are that happen inside the human txxiy such as hunger, changes in sugar levels etc
External stimuli are changes that happen outside the human body such as light levels, sound etc Response is the result or the outcnrne Of the stimulus
. Living things maintain internal conditions
Homeostasis is the ability to maintain stable internal cnnditions
Humans need to maintain constant
cnnditions such as: water levels, blood sugar, PH, temperature in order to survive
6. Living things use energy
• Living things need energy to survive
1. Light Microscope
• uses a light source to focus the object
It only has a magnification up to 1500 x which means that the object will only be bigger by 1500 times the original size
2. Electron Microscope
Uses beam of electrons to focus the object
It can magnify up to 100,000 x the original size of the object
TYPES OF ELECTRON MICROSCOPE
I. Scanning Electron Microscope (SEM)
Here the electrons pass the object and after reflected or bounce off the specimen to create a 3-D image
. Transmission Electron Microscope (TEM)
• Here the electrons are transmitted or is absorbed by the object
CELL THEORY
Robert Hooke
First person who investigated the cells using a cork stem
Image Of Robert Hooke "Cork" cells
Anton van Leeuwenhoek
Made the microscope that is more powerful than the one used by Robert Hooke
He also studied cells from rain water and discovered animal cules
CELL THEORY
I. All thing things are made up of cells
. Living things are the basic functioning unit of life
All cells come from pre-existing cells. (e.g. when we are wounded, the wounds heal)
TYPES OF CELLS according to Number
. Unicellular — only one cell, bacteria are the best example of unicellular organisms
. Multicellular — consists of many cells, cells of plants, animals, protists, and fungi are all multicellular
THREE BASIC PARTS OF THE CELL
1. Nucleus
2. Cytoplasm
the central part of the cell. the control center or the "brain- the cell because it is the one that controls all the activities within the cell
it contains the genetic information called the DNA that is responsible for the traits that parents pass to the offspring
The fluid or the watery part of the cell
This is where all the parts of the cell are found
In the cytoplasm. all chemical reactions take place such as the photosynthesis and respiration
3. Cell Membrane
• The outer part of the cell
It is the one that controls what comes in and out of the cell (including oxygen. carbon dioxide. waster materials etc)
• It is like a security guard
TYPES OF CELLS ACCORDING TO THE LOCATION OF DNA
These are organisms that do not have nucleus but they do have the DNA or the genetic material
The genetic material or the DNA is not by the nucleus but it is Iwated on the cytoplasm
Moreover. they do not have organelles (or parts)
They are typically smaller than eurkaryotes
are the example of prokaryotic
They have a definite nucleus where the DNA is found inside
They also have membrane- tmnd organelles
All forms of plants, animals, fungi and protist are eukaryote
CLASSIFICATION
All living things need to The biggest level of classification is the Dornain
Kingdom is the next level of classification to Domain
There are domains
Domain Archaea
Domain Bacteria
Domain Eukarya
There are Six Kingdoms of Living Things
Kingdom Archaea
Kingdom Bacteria
Kingdom Protista
Kingdom Fungi
Kingdom Plantae
Kingdom Animalia