Classroom Worksheet Chapter 3 Cellular Organization (Answers) PDF

Classroom worksheet Chapter 3 Cellular organization Name: ( ) Class: Date: 3.1 Cells as the basic units of life  Cells are the smallest functioning unit of life and have t...

Classroom worksheet Chapter 3 Cellular organization Name: ( ) Class: Date: 3.1 Cells as the basic units of life  Cells are the smallest functioning unit of life and have to be observed under (1) microscope. A. Discovery of cells and the cell theory  In the 17th century, the British scientist Robert Hooke examined slices of cork using a light microscope. He noted that cork was made up of many tiny boxes. He called them (2) cell.  Dutch scientist Anton van Leeuwenhoek was inspired by Hooke’s work and first observed living cells such as microbes, blood cells and sperm cells.  In the 19th century, cell theory was proposed:  All organisms are made up of one or more cells.  The cell is the basic unit of life.  Cells arise from (3) pre-existing cells. B. Microscope technology and the study of cells Light microscope (4) Transmission (5) Scanning electron microscope electron microscope Image Uses lenses to refract Uses a magnetic field to Scans the surface of a formation and focus light from the focus the beam of three-dimensional specimen electrons through a specimen with an thinly sliced specimen electron beam Con’t 3-1 Classroom worksheet 3 Cellular organization Light microscope (4) Transmission (5) Scanning electron microscope electron microscope Suitability  Examines living Reveals the detailed Reveals the external cells and preserved internal structures of a structures of a specimen cells specimen  Looks at biological processes in living cells Magnification Up to 1000 times Up to 10,000,000 times Up to 500,000 times 3-2 Classroom worksheet 3 Cellular organization 3.2 Using a light microscope  Components of a compound microscope: (6) Eyepiece (10) Coarse adjustment knob  magnifying lens that the  raises or lowers the body tube for eye looks through rough focusing Body tube (11) Fine adjustment knob (7) Nosepiece  brings the image into a sharp focus  can be turned to switch the objectives (8) Objective Arm  magnifying lens closest (12) Condenser to the specimen  concentrates the light reflected from the mirror Stage onto the specimen Stage-clip (13) Iris diaphragm (9) Mirror  regulates the amount of  reflects light to shine light passing through the through the specimen condenser Base  Total magnification of a compound microscope = Magnification of the (14) eyepiece × Magnification of the (15) objective 3-3 Classroom worksheet 3 Cellular organization Practical 3.1 Observation with a light microscope Refer to Coursebook p.3-8 and SBA Practical Workbook p.3-1. Results and discussion  When the typed letter ‘b’ is observed under the microscope, the image appears as (16) q. This shows that the image formed by a light microscope is upside down and reversed from left to right (laterally). We call this an (17) inverted image. (Upside down and laterally inverted)  When the same specimen is examined at low power magnification and high power magnification, the images observed differ in some ways: (18) Low (19) High power power magnification magnification Area of specimen observed Larger Smaller Details of the image Fewer More observed Brightness of the image Brighter Dimmer Practise…  Checkpoint (Coursebook p.3-10) Unit conversion 1m 1cm = 10-2m 1mm = 10-3m = 10-1cm 1m = 10-6m = 10-4cm = 10-3mm 1nm = 10-9m = 10-7cm = 10-6mm = 10-3m 1m = 100cm = = = 1000mm 1,000,000m 1,000,000,000nm 1cm = 10mm = 10,000m = 10,000,000nm 1mm = 1000m = 1,000,000nm 1m = 1000nm 1nm 3-4 Classroom worksheet 3 Cellular organization Two types of questions related to magnification Type 1 Type 2 Given the scale, Given the magnification of the microscope, find the measured length from the scale find the measured length and the magnification of the and then the actual length of certain microscope. organelle. and the magnification of the microscope. Based on the scales provided below, work out 1. The magnification of the microscope is your steps to find the magnification of the 1000X, find the actual length of the microscope. following organelles. 1. 2cm 1000 1 m 2cm  1m = 20000m  1000 = 20000m  1m = 20m = 20000x 2. 2. The magnification of the microscope is 0.05mm 200X, find the actual length of the 1.5cm  0.05mm following organelles. = 15 mm  0.05mm = 300x 1.5cm 200 = 15000m  200 = 75m 3. 3. The magnification of the microscope is 0.25 m 400X, find the actual length of the 5cm  0.25m following organelles. = 50000m  0.25m = 200 000x 3cm  400 = 30000 m  400 = 75m 3-5 Classroom worksheet 3 Cellular organization Please refer to Activity 3.1 on p.3-7 and complete the questions involved. 3.3 Sub-cellular structures in animal cells and plant cells A. The basic structure of a cell (20) cytoplasm ribosome (21) cell membrane mitochondria (22) nucleus vacuole rough endoplasmic reticulum smooth endoplasmic reticulum Animal cell (26) chloroplast (25) mitochondrion ribosome (24) vacuole nucleus (23) cell wall (27) rough endoplasmic reticulum cytoplasm (28) smooth endoplasmic reticulum cell membrane Plant cell 3-6 Classroom worksheet 3 Cellular organization B. Sub-cellular structures and their functions  Small sub-cellular structures inside the cytoplasm of a cell are called (29) organelles. Organelle Features and functions Cell membrane  A thin and flexible layer which is (30) differentially / selectively permeable  Controls the movement of substances into and out of the cell Cytoplasm  Jelly-like substance  Holds most of the organelles in a cell  Site where many (31) biochemical reactions take Place Nucleus  Surrounded by (32) nuclear membrane (double membrane)  Contains the (33) genetic material of life (DNA) that determine the characteristics of organisms  Controls protein synthesis and all activities of the cell  With small holes on the nuclear membrane called nuclear pores  allow exchange between the nucleus and the cytoplasm  With darkly stained regions called nucleolus / nucleoli  involve in making ribosomes Ribosomes  Sites of (34) protein synthesis Endoplasmic 1. Rough ER: reticulum  Attached with (35) ribosomes on the surface  Transport the (36) proteins produced at the ribosomes 2. Smooth ER:  Involved in the synthesis and transport of (37) lipids within the cytoplasm 3-7 Classroom worksheet 3 Cellular organization Organelle Features and functions Mitochondrion  (38) Rod -shaped  Surrounded by a smooth outer membrane and a (39) highly-folded inner membrane to increase surface area  Main site of aerobic respiration to produce (40) energy (ATP) by breaking down foods Vacuole  A membrane-bounded sac which contains (41) cell sap (with water and dissolved substances)  Provides support to the plant when it is fully filled Cell wall  Made up of (42) cellulose  Fully permeable to water and dissolved substances  Protects and gives shape to plant cells Chloroplast  Found in some cells of green plants  Surrounded by a double membrane  Inside with flattened sac-like structures to increase surface area  Contains (43) chlorophyll which absorbs light energy for (44) photosynthesis 3-8 Classroom worksheet 3 Cellular organization C. Similarities and differences between animal cells and plant cells Features Animal cells Plant cells Cell membrane (45) Present / Absent (46) Present / Absent Mitochondria (47) Present / Absent (48) Present / Absent Nucleus (49) Present / Absent (50) Present / Absent Except red blood cells Position of nucleus in the At the centre At one side cell Shape Fixed by (51) cell wall Irregular Size (52) Smaller / Larger (53) Smaller / Larger Cell wall (55) Present / Absent (54) Present / Absent Even in dead plant cells Vacuole None or a few small vacuoles A large central vacuole Chloroplast Absent Present in green plant cells Practical 3.2 Preparation of a temporary mount of animal cells Refer to Coursebook p.3-18 and SBA Practical Workbook p.3-7. Practical 3.3 Preparation of temporary mounts of plant cells and tissues Refer to Coursebook p.3-19 and SBA Practical Workbook p.3-11. Practise…  Checkpoint (Coursebook p.3-21) 3-9 Classroom worksheet 3 Cellular organization 3.4 Prokaryotic cells and eukaryotic cells  Organisms made up of (56) eukaryotic cells like animal cells and plant cells are called (57) eukaryotes.  (58) Unicellular organisms are made up of a single cell while (59) multicellular organisms are composed of many cells.  Organisms made up of (60) prokaryotic cells are called (61) prokaryotes (e.g. bacteria). Comparison between prokaryotic cells and eukaryotic cells: Eukaryotic cells Prokaryotic cells Nucleus Surrounded by the Not membrane bounded (62) nuclear membrane DNA Enclosed in the nucleus Lies freely in the cytoplasm Size (63) Smaller / Larger (64) Smaller / Larger Membrane-bound Present Absent organelles Cell wall Present in plant cells Present, but not made up of cellulose Capsule Absent Present Flagella Absent Present Practise…  Checkpoint (Coursebook p.3-23) 3-10 Classroom worksheet 3 Cellular organization 3.5 Levels of organization in organisms Level of organization in humans: 1. Molecule (e.g. DNA)  Biomolecules that are important to life 2. (65) organelle (e.g. a nucleus)  Perform various functions in a cell 3. Cell (e.g. a heart muscle cell)  The functioning unit of life 4. (66) Tissue (e.g. heart muscle tissues)  Groups of similar cells that are organized to perform a specific function 5. (67) Organ (e.g. a human heart)  Multiple tissues that cooperate to perform a task 3-11 Classroom worksheet 3 Cellular organization 6. System (e.g. circulatory system)  Groups of several organs to carry out a vital body function 7. Organism (e.g. a human)  Different systems work together to sustain life Challenge yourself Construct a flowchart to show the level of organization in plants. Chlorophyll (molecule)  (a) chloroplast (organelle)  Mesophyll cells  Mesophyll tissue  (b) Leaf (organ)  (c) shoot system  Plant Practise…  Checkpoint (Coursebook p.3-26) 3-12