Unit 1 and Topic 1: Cells as the basis of life

Question 1

Describe the structure of the cell membrane based on the fluide mosaic phospholipid bilayer model.

Answer 1

The cell membrane is composed of 4 main components:

Phospholipid bilayer - hydrophobic tails, hydrophilic heads contributing to semi-permeability

Cholesterol - fluidity

Transport proteins - for facilitated transport

glycoproteins - help with signalling, adhesion and recognition.

Question 2

Passive diffusion

Answer 2

With the concentration gradient, requires no energy.

osmosis, simple diffusion, facilitated diffusion

Question 3

Active transport

Answer 3

Against the concentration gradient, requires ATP

pumps, bulk transport

Question 4

Endocytosis

Answer 4

Transport into the cell

pinocytosis: for liquids

Phagocytosis: for solids, cell membrane invaginates to form a vesicle which gets transported into the cell carrying all the molecules.

Question 5

Exocytosis

Answer 5

Transport out of the cell

Question 6

Physical factors affecting the diffusion of substances

Answer 6

size
shape

Question 7

Chemical factors affecting the diffusion of substances

Answer 7

polarity
charge
hydrophilic vs hydrophobic
and also the concentration G

Question 8

SA:V

Answer 8

cell have a really high SA:V ratio for increased efficiency of nutrient absorption and wastee removal

Question 9

Requirements for cell survival

Answer 9

1. energy - glucose, light and chemical sources
2. matter - CO2 and O2, for respiration and photosynthesis
3. Simple nutrients - sugars
4. macromolecules and simple molecules - amino acids, fatty acids and glycerol, nucleic acids, water, ions
5. waste removal - nitrogenous waste, heat, CO2, O2, ions and water

Question 10

Prokaryotes

Answer 10

no membrane-bound organelles
no nucleus
single circular chromosome
really small
have ribosomes and DNA

Question 11

Eukaryotes

Answer 11

membrane-bound organelles
nucleus
linear chromosomes
larger

Question 12

Organelles

Answer 12

mitochondria - cellular respiration
choloroplasts - photosynthesis
ribosomes - protein synthesis
lysosome - waste removal
RER - protein synthesis, studded with ribosomes
SER - carbohydrate and lipid synthesis
plastids - pigment synthesis

Question 13

Significances

Answer 13

size of prokaryotes helps to increase efficiency as it does not have organelles to help it do so

organelles helps increase the efficiency of processes so happen more specifically and with greater efficiency due to compartmentalisation

Question 14

Endosymbiotic theory

Answer 14

prokaryote ate another prokaryote and they formed an endosymbiotic relationship, this is why mitochondria and chloroplasts have DNA and internal membranes.

Explains why eukaryotes have membrane bound organelles

leads to genetic variation in prokaryotic cells

and also allows for varied structures and functions.

Question 15

formula for the image

Answer 15

I = AM

Question 16

3 advantages of membrane-bound organelles

Answer 16

1. compartmentalisation so efficiency
2. uses low number of enzymes that can be recycled
3. allows for the concentration of reactants and storage of products

Question 17

mitochondrion

Answer 17

site for cellular respiration
have inner membrane, folded (christae), studded with enzymes. This increases the efficiency of cellular respiration.

Question 18

enzymes

Answer 18

reusable proteins that increase the rate of reaction as it reduces the activation energy required for processes. They are also highly specific which help in aiding multiple biochemical processes.

Question 19

enzyme models

Answer 19

lock and key - exact fit

induced fit - becomes perfect

Question 20

active site

Answer 20

part of the enzyme that binds to the substrate, they are very specific to the enzyme to make sure they dont start working when theyre not supposed to.

Question 21

factors that affect ROR of enzymes

Answer 21

temp - range
pH - range
enzyme concentration - linear
substrate concentration - plateaus when enzymes are working at their maximum capacity
cofactors - some enzymes dont work without a cofactors
inhibitor - competitive and non - competitive

Question 22

equation for photosynthesis

Answer 22

6CO2 + 12H20 > C6H12O6 + 6H2O + 6O2

Question 23

stages of photosynthesis

Answer 23

light dependent - thylakoid membranes, splits water into H+ and O2 and ATP and NADPH

Light independent - cytoplasm, uses H+ and CO2 and ATP and NADPH into C6H12O6 and H20

Question 24

equation for cellular respiration

Answer 24

C6H12O6 + 6O2 > 6H20 + 6CO2 + 36-38ATP

Question 25

anaerobic respiration

Answer 25

produces lactic acid (glycolysis and fermentation)

Question 26

photosynthesis and respiration are equal at the light compensation point, what does this mean?

Answer 26

during the day photosynthesis>respiration and opposite for the night.