Grade 11, Unit 1 topic 1

Question 1

Explain the effect of surface-volume ratio on diffusion.

Answer 1

Bigger SA:V = more efficient diffusion (smaller cell)
Smaller SA:V = less efficient diffusion (larger cell)

As volume and surface area increase, the volume increases faster.
As the surface area to the volume ratio gets smaller as the cell gets larger.

Thus, if the cell grows beyond a certain limit, not enough material will be able to cross the membrane fast enough to accommodate the increased cellular volume. A cell will eventually become so large there is not enough surface area to allow the diffusion of sufficient substances like oxygen and it will die.

Question 2

Define cellular respiration

Answer 2

A series of biochemical reactions and process using glucose and oxygen and producing carbon dioxide and water.

Oxygen diffuses from a high concentration to low concentration in cytoplasm

Question 3

What is a Heteroph and autoroph?

Answer 3

An heteroph is an organism that cannot synthesis its own organic compounds from simple inorganic materials. It depends on other organisms for nutrients and energy requirements.

Na autoroph is an organism that can synthesis its own organic compounds. (Use photosynthesis)

Question 4

Define Macromolecules + four types

Answer 4

Are large molecules that build cellular structures and to maintain bio mechanical processes.

Carbohydrates
Lipids
Proteins
Nuclei acids.

Question 5

Define monosaccharides

Answer 5

Refers to a single sugar that cannot be broken down into smaller molecules.

Question 6

Define Disaccharides

Answer 6

Two linked monosaccharides

-sucrose

Question 7

Define polysaccharides

Answer 7

A complex carbohydrate made by linking together simple sugars

• starch (stored in roots and breaks down into glucose)
• cellulose (tough cell Wall)

Question 8

What elements are in all fatty acids and are they soluble?

Answer 8

Carbon, hydrogen, oxygen And are insoluble.

Question 9

Define triglycerides

Answer 9

A molecule of three fatty acid chains of carbon and hydrogen combined to a glycerol that

Question 10

Define a phospholipid

Answer 10

A phospholipid is a lipid made up of a glycerol, two fatty acid chains and a phosphate head.

Question 11

Define RNA and its function

Answer 11

Stands for ribonucleic acid and is a single trended nuclei acid involved in protein synthesis. In RNA thymine is replaced by uracil.

Ribonucleic acid is used as a messenger to carry instructions for proteins synthesis to the ribosome in the cytoplasm.

Question 12

Define cytosol

Answer 12

The part of the cytoplasm containing highly organised fluid material with dissolved substances; excluding the organelles.

Question 13

What are the major mineral elements

Answer 13

Fe (2+ or 3+), Mg (2+), K (1+), Na (1+), Cl (1-), Nitrate (-3), H2PO4 (-4) and SO4 (-2).

Question 14

What are examples of wastes

Answer 14

Ammonia, carbon dioxide, oxygen,uses, Uric acid, water ions and heat

Question 15

What is the function of the mitochondria?

Answer 15

The mitochondria is an organelle found in the cytoplasm of a cell and is the site for aerobic cellular respiration.

Question 16

What is the function of the chloroplast?

Answer 16

Responsible for the conversion of solar to chemical energy during photosynthesis.

Question 17

Function of the rough endoplasmic reticulum

Answer 17

Endoplasmic reticulum with ribosomes attached that makes proteins.

Question 18

What is the function of the smooth endoplasmic reticulum?

Answer 18

An endoplasmic reticulum with no ribosomes attached responsible for the manufacture and metabolism of carbohydrates, lipids and steroids.

Question 19

What is the function of Plastids?

Answer 19

Plastics are double membrane bound organelles present in plants involved in the synthesis of pigments, tannins and polyphenols.

Question 20

What features reflects an evolutionary past of mitochondria and chloroplasts

Answer 20

EndoSymbiosis theory proposes eukaryotes emerged due to a bacteria cell was ingested by a prokaryote. (How M and C was formed)

• M and C make copies of themselves then split like bacteria.
• M and C have 2 membranes (one from host when it engulfed bacteria and one is ingested bacteria)
• M is similar size and has circle genetic material like bacteria

Question 21

What is the function of a lysosome?

Answer 21

Removal of wastes in a Eukaryote

Question 22

Describe the structure of the phospholipid bilayer model.

Answer 22

The membrane consists of a double lipid lipids with the ability to flow and change shape. Specialised protein molecules including channel proteins and carrier proteins are embedded in the lipid.

The phospholipids are a type of lipid that consist of two hydrophobic tails and a hydrophilic head, which causes the fatty tails turn away from the watery environment and cytoplasm.

Cholesterol is another type of lipid that is essential for the structure of the bilayer as it strengths and stabilises the membrane which maintains its fluid structure. Also consists of glycoproteins which are protein and carbohydrates chains that serve as receptors for other types of molecules and are involved in adhesion of the membrane.

Question 23

Define passive movement

Answer 23

Passive movement refers to movement of molecules that does not require the expenditure of energy and moves down a concentration gradient.

Question 24

Define active movement

Answer 24

Active movement is movement against a concentration gradient, which therefore requires the expenditure of energy.

Question 25

Define diffusion

Answer 25

Diffusion is the passive movement of molecules down a concentration gradient from an area of high concentration to an area of low concentration.

Question 26

Provide examples of molecules that easily move across the cell membrane

Answer 26

Oxygen Water Carbon dioxide

Question 27

Provide examples of molecules that do not easily move across the cell membrane

Answer 27

Charged particles - Sodium ion (positive), potassium ion (positive) Large particles - glucose and amino acids.

Question 28

Define facilitated diffusion

Answer 28

Facilitated diffusion refers to the form of diffusion that assist charged or large particles that do not readily move across the membrane, across the cell membrane through the use of carrier or channel proteins.

Question 29

Explain the process of facilitated diffusion

Answer 29

Facilitated diffusion is the process by which particles that do not readily pass through the membrane, are assisted by carrier or channel proteins to pass through the membrane. Channel proteins form passage ways through which small ions can diffuse rapidly from an area led high ion concentration to low ion concentration. Only ions of a particular shape and size can pass through. Carrier proteins bind to specific molecules on one side of the membrane, change shape and release the substance on the other side of the mer sine. EG: glucose transporter In mammal plasma membranes.

Question 30

Define osmosis

Answer 30

Osmosis refers to the movement across a selectively permeable membrane from a region of low solute concentration to high solute concentration. (Active transport)

Question 31

Define solvent, solute and solution

Answer 31

The solvent is the substance in which another substance can be dissolved into to create a solution. Eg: sugar The solute is then substance that is being dissolved into the solvent. Eg: water The solution is the mixture of solute and solvent. Eg: water and sugar solution

Question 32

Define a dilute solution

Answer 32

A dilute solution has relatively high concentration of water molecules compared to solute particles.

Question 33

Define a concentrated solution.

Answer 33

A concentrated solution has a high amount of solute particles compared to water particles.

Question 34

Define isotonic

Answer 34

Iso = same Fluid with an equal solute concentration to another fluid. Water jostles on both sides of the membrane and move in each direction equally.

Question 35

Define hypotonic

Answer 35

Hypo = Lower When cells are surrounded by a fluid that has a lower solute concentration compared to the cytoplasm. Water molecules will diffuse through the membrane into the cells.

Question 36

Define hypertonic

Answer 36

When the cells are surrounded by a fluid that has a higher solute concentration in compared to their cytoplasm. (External solution is higher) Water molecules will diffuse out of the cells.

Question 37

what are the requirements of a cell in order to survive

Answer 37

cells need energy matter nutrients removal of wastes

Question 38

define deamination

Answer 38

a process that removes the nitrogen-containing amine group from the rest of the amino acid

Question 39

define ammonia and its chemical formula

Answer 39

a product of amino acid breakdown that is extremely toxic in humans (NH3)

Question 40

define urea

Answer 40

a nitrogenous waste produced when amino acids are broken down in mammals; it is excreted in urine

Question 41

define uric acid

Answer 41

a nitrogenous waste product produced by desert animals, birds, reptiles and insects

Question 42

define condensation reaction

Answer 42

a reaction in which a molecule of water is eliminated when two monomers are bonded together

Question 43

describe the process of deamination

Answer 43

Protein contains nitrogen and the first product of deamination is ammonia, which is toxic to cells. Organisms must either excrete ammonia very quickly or convert it to less toxic substances such as urea and uric acid, which can be stored temporarily prior to elimination. The form in which nitrogen is excreted from the body depends on the species and the amount of water available to it. Many aquatic vertebrates, which have a lot of water available ( for example, most fish, larval amphibians such as the tadpole, some reptiles such as turtles and crocodiles), excrete nitrogen as ammonia, because it is very soluble in water. In many organisms, such as humans, ammonia is converted to urea, which is less toxic and requires much less water to be excreted. Other vertebrates ( for example, birds and some reptiles such as lizards and snakes) live in dry environments with very little water. In these animals, ammonia is converted to uric acid, which is much less toxic and insoluble in water.

Question 44

define metabolism

Answer 44

Metabolism is the sum of chemical reactions that maintain life within an organism. All chemical reactions generate heat as a by-product and this is referred to as metabolic heat. Cellular respiration generates a significant amount of metabolic heat. Most of a cell’s chemical reactions require the help of enzymes, which often have specific temperature requirements. Therefore, it is important that cells and organisms remove excess metabolic heat. Single cells and small organisms readily lose heat to the environment, but larger organisms such as birds and mammals that maintain a constant internal temperature often have complex systems dedicated to temperature regulation.

Question 45

define prokaryotes

Answer 45

a simple type of cell that lacks a nucleus and membrane-bound organelles; a member of domains Archaea or Bacteria

Question 46

define plasmid

Answer 46

a small ring of DNA that is not a chromosome, most often found in prokaryotes

Question 47

how does the cell membrane maintain relatively stable internal conditions

Answer 47

The cell membrane maintains stable internal condition through homeostasis. Homeostasis depends on maintaining correct fluid levels within the cell and on exchanging useable materials, such as oxygen, for waste products, such as carbon dioxide. The cell membrane is selectively permeable, which allows control over what substances pass through the membrane and maintain homeostasis. Plasma membranes allow water, oxygen and carbon dioxide to pass through by osmosis, or passive diffusion.

Question 48

how does the cell membrane maintain relatively internal stable conditions

Answer 48

the cell membrane maintains relatively internal stable conditions through active transport. Active transport requires the help of carrier proteins, or “pumps”. These pumps are used like gateways, for passing in and out of cells such as the sodium-potassium pump. This pump is found in the plasma membrane of animal cells, and maintains the level of sodium ions and potassium ions. These pumps are built to perfectly fit sodium and potassium, and to block out anything else. Active transport is key to the function of a cell. It helps the cell control how much of certain ions such as water, sodium, or potassium pass through the cell membrane. Without active transport, a cell would not be able to maintain homeostasis.

Question 49

define exocytosis

Answer 49

Exocytosis occurs when a vesicle fuses with the plasma membrane, allowing its contents to be released outside the cell. can be used to Removing toxins or waste products from the cell’s interior

Question 50

explain endocytosis

Answer 50

The movement of solids or liquids from the environment into a cell via vesicle formation. Because of their size and charge, large polar molecules cannot pass through the hydrophobic cell membrane or via membrane transport proteins. When a cell takes up a substance by endocytosis, it changes shape by sending out projections that surround the material. When the cell membrane of the projections meet, the membrane fuses and forms a vesicle, which then stores or transports the substance within the cytoplasm.

Question 51

# define phagocytosis + example

Answer 51

Phagocytosis is a form of endocytosis and is responsible for the bulk transport of solids into a cell inside a vesicle. Phagocytosis is the transport of solid particles into a cell inside a vesicle. During phagocytosis, a cell sends out projections that surround the solid material and when the projections meet, the plasma membrane fuses. This results in the formation of a phagocytic vesicle, which stores or transports the substance within the cytoplasm. EG: Macrophages, are referred to as phagocytes because, in defending the body against disease, they engulf bacteria by phagocytosis

Question 52

define exocytosis

Answer 52

the movement of solids or liquids from a cell to the environment via vesicle formation. Exocytosis is the process by which large molecules held in vesicles within the cell are transported to the external environment. During exocytosis, a membrane-bound vesicle moves to the plasma membrane, fuses with it and then releases its contents to the exterior of the cell.

Question 53

what are the requirements for cell survival?

Answer 53

energy sources (light or chemical) - matter (gases such as carbon dioxide and oxygen) - simple nutrients in the form of monosaccharides, disaccharides, polysaccharides - amino acids, fatty acids, glycerol, nucleic acids, ions and water - removal of wastes (carbon dioxide, oxygen, urea, ammonia, uric acid, water, ions, metabolic heat).

Question 54

define endosymbiotic theory

Answer 54

theory that suggests that chloroplasts and mitochondria arose from ancient prokaryote cells that were ingested by other prokaryote host cells. Instead of being digested, the bacteria formed a symbiotic relationship with its host. Mitochondria contain ribosomes and RNA molecules so that they can make their own proteins. It is likely mitochondria evolved from bacteria that could carry out aerobic cellular respiration, living within a host cell.

Question 55

what features of mitochondria and Chloroplasts suggest they have an evolutionary past?

Answer 55

1. when they reproduce, mitochondria and chloroplasts make copies of themselves and split in two, just like bacteria 2. Mitochondria and Chloroplasts have their own genetic material, which, like that in prokaryotes bacteria, is contained in a circular DNA molecule. 3. Both mitochondria and chloroplasts have two membranes. The outer one is probably derived from the host membrane when it engulfed the bacteria and the inner one is probably the membrane of the ingested bacteria.

Question 56

describe prokaryotes

Answer 56

can be archaea or bacteria prokaryotic cells lack internal membrane bound organelles, do not have a nucleus, are significantly smaller than eukaryotes, usually have a single circular chromosome and exist as single cells

Question 57

describe eukaryotes

Answer 57

a complex type of cell with a nucleus and membrane-bound organelles; a member of domain Eukarya Eukaryotic cells have specialised organelles to facilitate biochemical processes: - photosynthesis (chloroplasts) - cellular respiration (mitochondria) - synthesis of complex molecules including proteins (rough endoplasmic reticulum), carbohydrates, lipids and steroids (smooth endoplasmic reticulum), pigments, tannins and polyphenols (plastids) - the removal of cellular products and wastes (lysosomes)

Question 58

where does cellular respiration in cells occurs? how do cristae facilitate cellular respiration

Answer 58

mitochondria the cristae are the folding of the inner membrane into the matrix, which increases the surface area facilitating cellular respiration and enzyme controlled reactions.

Question 59

what process occurs in the chloroplast of eukaryotic cells? what does the chlorophyll do

Answer 59

photosynthesis the chlorophyll converts solar energy into chemical energy

Question 60

what is the role of temporary vacuole are they in prokaryotic or eukaryotic cells

Answer 60

eukaryotes temporary storage sac

Question 61

what is the role of the golgi apparatus

Answer 61

system of membranes that package and store substances before their release

Question 62

what is the role of the endoplasmic reticulum

Answer 62

intracellular and intercellular transport system

Question 63

what is the role of ribosomes

Answer 63

site of protein synthesis

Question 64

what does the rough endoplasmic reticulum do what do the ribosomes do

Answer 64

ribosomes are responsible for the assembly of proteins the rough ER synthesises proteins

Question 65

what does the smooth endoplasmic reticulum do

Answer 65

Smooth ER is responsible for the manufacture and metabolism of lipids and carbohydrates and the synthesis of steroids.

Question 66

what is the role of plastids

Answer 66

Synthesis of pigments, tannins and polyphenols by plastids

Question 67

what is the role of a lysosome

Answer 67

Lysosomes contain digestive enzymes that are responsible for splitting complex chemical compounds into simpler ones. These simpler subunits can then be used as building blocks for new compounds and organelles. Eg: after a liver mitochondria is broken down after approx. 10 days

Question 68

what factors can affect ROR?

Answer 68

reaction rates of enzymes can be affected by factors, including temperature, pH, the presence of inhibitors, and the concentrations of reactants and products

Question 69

describe the lock and key model

Answer 69

The folding of an enzyme protein forms a fixed groove or pocket-shaped active site. This groove can accommodate one or more particular substrate molecules. The active site is highly specific for a particular substrate. The substrate must be of a compatible shape for binding to occur.

Question 70

describe the induced fit model

Answer 70

The other model of how an enzyme–substrate complex is formed is known as the induced-fit model of enzyme action. This model is more widely accepted. In this case, the enzyme shape is not fixed. The bonds that form between an enzyme and its substrate are thought to modify the shape of the enzyme so that the substrate can be fully accommodated by the enzyme

Question 71

what is the main function of an enzyme

Answer 71

to decrease the activation energy

Question 72

examples of enzymes

Answer 72

pepsin - digests proteins found in ingested food. amylase - digest proteins found in ingested food.

Question 73

define non-competitive inhibitor

Answer 73

molecule that binds to an enzyme at a site other than the active site; this changes the shape of the enzyme so that the substrate can no longer bind to the active site

Question 74

define competitive inhibitor

Answer 74

competitive inhibitor | a substance that competes with a substrate for an enzyme’s active site

Question 75

what is the role of the chloroplast

Answer 75

Chloroplasts are the site of photosynthesis. Chloroplasts have an outer and an inner membrane.

Question 76

what is the stroma

Answer 76

The stroma is a gel-like matrix rich in enzymes and is enclosed by the inner membrane.

Question 77

what are the thylakoid

Answer 77

Suspended in the stroma is a membrane system, the thylakoid membranes. These are flat, sac-like structures that are called grana when grouped together into stacks

Question 78

what is the sequence of aerobic respiration

Answer 78

as aerobic respiration (glycolysis, Krebs cycle and electron transfer chain) requires oxygen