Grade 10 Biology

Question 1

Cell Membrane (3)

Answer 1

1. Semi-permeable phospholipid bilayer
2. forms a protective barrier around the cell that is composed of a double layer of lipids (fat-like molecules)
3. Semi-permeable because it regulates the passage of substances into and out of the cell.

Question 2

Cytoplasm

Answer 2

jelly-like liquid in which the cell organelles are suspended

Question 3

Cytoskeleton (3)

Answer 3

1. basic structural framework of the cell
2. necessary for cell shape, mechanical support, cell division, movement of the cell as a whole, and movement of organelles within the cell
3. composed of a network of fibers made of protein filaments

Question 4

Nucleus (5)

Answer 4

1. control centre
2. directs all cellular activities
3. contains genetic material (DNA) of the cell
4. DNA is organized into discrete units called
5. chromosomes: structures that carry coded instructions for all cell activity

Question 5

Nuclear Membrane (2)

Answer 5

1. surrounds the nucleus

2. composed of two porous layers allowing for certain substances to pass through

Question 6

Nucleolus (3)

Answer 6

1. a densely packed ball of DNA, RNA and protein
2. used to make ribosomes
3. only visible when the cell isn’t dividing

Question 7

Chromosomes (5)

Answer 7

1. found in the nucleus
2. composed of DNA and protein and contain all genetic information passed on from parent to offspring
3. there are a set number of chromosomes per species, ex: human cell has 46 chromosomes but human sex cell (egg or sperm) has only 23
4. the portion of a chromosome that “codes” for a particular trait is called a gene
5. When the cell isn’t dividing, chromosomes are present as chromatin, long uncoiled thread-like strands of DNA.

Question 8

Centrosome/Centrioles (4)

Answer 8

1. found near nucleus, only in animal cells
2. organizes microtubules in the cell
3. made up of a pair of centrioles: paired cylindrical organelles near the nucleus composed of microtubules, lie at right angles to each other
4. involved in cell division (needed to make spindle fibers)

Question 9

Mitochondrion (4)

Answer 9

1. a double-layered, sausage-shaped structure that encloses inner folds called cristae
2. known as the “powerhouse” of the cell because it produces the chemical energy (ATP) that fuels cellular activities by a process called cellular respiration:
3. Glucose + oxygen → carbon dioxide + water
   + energy
4. C6H12O6 (s) + 6O2 (g) → 6CO2 (g) + 6H2O (g)
   + energy

Question 10

Endoplasmic Reticulum (4)

Answer 10

1. a network of interconnected small tubes extending from nuclear membrane to cell membrane
2. manufactures and transports materials such as proteins and fats throughout the cell
3. rough ER: contains ribosomes
4. the smooth ER does not have ribosomes on it

Question 11

Smooth ER (2)

Answer 11

1. contains many enzymes and is involved in several metabolic processes such as the synthesis of lipids, phospholipids and steroids
2. also stores calcium ions

Question 12

Rough ER

Answer 12

Responsible for synthesizing and transporting proteins

Question 13

Ribosomes (3)

Answer 13

1. manufacture proteins
2. can be found embedded in the rough endoplasmic reticulum or dispersed throughout the cytoplasm
3. make up 25 % of the total mass of the cell

Question 14

Golgi Bodies/ Golgi Apparatus (3)

Answer 14

1. membrane structures found near the nucleus
2. composed of numerous layers
3. they receive proteins (via transport vesicles) from the endoplasmic reticulum and modify, sort and package these proteins for delivery throughout and out of the cell

Question 15

Lysosome (4)

Answer 15

1. small membrane bags containing enzymes
2. aid in digestion of proteins, fats and carbohydrates
3. involved in the recycling of organelles, the destruction of cells, and also help fight infection by breaking down invading bacteria
4. often called the “suicide sacs”

Question 16

Vacuoles

Answer 16

sacs that serve as storage areas for water, minerals and waste

Question 17

Cilia And Flagella (3)

Answer 17

1. Cilia and flagella are whip-like appendages that extend from the surface of many eukaryotic and some prokaryotic cells.
2. They are used for locomotion in single-celled organisms or to move fluid and materials past immobile cells.
3. Examples: - Sperm cells move using a flaggeum
   - H.Pylori, a bacteria found in some infected stomachs move using many flagella

Question 18

Central Vacuole (3)

Answer 18

1. Plants have one central vacuole instead of several smaller ones as in animal cells.
2. In a mature plant cell, the vacuole typically makes up more than 90 % of the volume.
3. It’s primary function is to provide turgidity
   (stiffness to the cell), as well as to store food, water and waste.

Question 19

Chloroplasts (4)

Answer 19

1. contain the green pigment chlorophyll
2. convert energy from the sun into a stored form of chemical energy called glucose
3. also produce atmospheric oxygen through
   photosynthesis:
4. Carbon dioxide + water + light energy → glucose + oxygen

Question 20

Cell Wall (3)

Answer 20

1. found only in plant cells - is porous and made up of cellulose fibres which gives it a rigid structure
2. provides strength, support and protection to the cell and surrounds the cell membrane
3. materials cannot get through cell walls, openings called plasmodesmata are used for communication and to transport materials between plant cells

Question 21

CELL MEMBRANE (2)

Answer 21

1. A membrane is a collage of different proteins embedded in the fluid matrix of the lipid bilayer
2. membrane parts are made in the ER and Golgi Bodies

Question 22

Selective Permeability (4)

Answer 22

1. A cell must exchange materials with its surroundings, a process controlled by the plasma membrane
2. The plasma membrane exhibits selective permeability
3. It allows some substances to cross it more easily than others
4. The selectively permeable membrane is important in the cell’s ability to maintain homeostasis (or the condition of equilibrium).

Question 23

Fluid Mosaic Model of Membrane Structure (3)

Answer 23

1. Cellular membranes are “fluid mosaics” of lipids and proteins moving within the membrane
2. membranes are composed of proteins and lipids
3. membrane proteins and lipids are synthesized in the ER and Golgi apparatus

Question 24

Freeze-fracture studies of the plasma membrane

Answer 24

A cell membrane can be split into its two layers, revealing the ultrastructure of the membrane’s interior.

Question 25

MEMBRANE COMPONENTS (8)

Answer 25

1. Phospholipids 2. Cholesterol 3. Carbohydrates 4. Proteins - Peripheral - Integral * Active transport integral proteins * Passive transport integral proteins

Question 26

Phospholipids (6)

Answer 26

1. are molecules arranged in a double layer (i.e. bilayer) 2. are the most abundant component in the plasma membrane 3. contain a phosphate head & two hydrocarbon tails 4. Are amphipathic (means that they contain both 5. hydrophobic and hydrophilic regions) Phosphate heads = face the watery environment inside & outside the cell 6.Hydrocarbon tails = face one another, away from the watery environment

Question 27

Hydrophobic (4)

Answer 27

1. repelling, tending to not combine with water 2. molecule is usually neutral in charge 3. lipid soluble and pass membrane rapidly 4. “water fearing”

Question 28

Hydrophilic (4)

Answer 28

1. attracted to water 2. molecule usually has an overall charge 3. not lipid soluble & doesn’t pass membrane rapidly 4. “water loving”

Question 29

Membrane Fluidity (2)

Answer 29

1. Phospholipids in the plasma membrane can move within the bilayer 2. The type of hydrocarbon tails in phospholipids affects the fluidity of the plasma membrane

Question 30

Cholesterol

Answer 30

cholesterol helps keep the phospholipids spaced apart which adds to the fluidity of the membrane

Question 31

Carbohydrates (4)

Answer 31

1. Cell signaling 2. Cell adhesion 3. Cell-cell recognition: A cell’s ability to distinguish one type of cell from another 4. Cells do this by interacting with the surface molecules of other cells

Question 32

Proteins (7)

Answer 32

1. many different kinds of proteins are embedded within the lipid bilayer 2. Transport materials into & out of cell 3. Enzymatic Activity 4. Signal Transduction 5. Cell-cell recognition 6. Intercellular joining 7. Attachment to the cytoskeleton & extracellular matrix (ECM)

Question 33

Transport Protein (3)

Answer 33

1. A protein that spans the membrane may provide a hydrophilic channel across the membrane that is selective for a particular solute. 2. Other transport proteins shuttle a substance from one side to the other by changing shape. 3. Some of these proteins hydrolyze ATP as an energy source to actively pump substances across the membrane.