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biology revision unit 1 (THIS ONE) Flashcards

1
Q

2 differences between eukaryotic and prokaryotic cells

A

Prokaryotic
- No membrane bound organelles
- Have a cell wall
- relatively basic cells with little cellular organisation
-unicellular
Eukaryotic
- Membrane bound organelles and nucleus
- More complex
- multicellular or unicellular

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2
Q

How does SA:V ratio affect absorption in a cell

A

The higher the SA:V ratio, the greater efficiency of two-way exchange of materials across the plasma membrane.

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3
Q

How does SA:V ratio provide limitations on cell size

A

As cell size increases:
Its volume increases at a faster rate than the surface area.
so
There is less surface area, so the surface areato volume ratio decreases
so
Large cells will have difficulties in exchanging materials at rates adequate to meet demands. Cell size is limited by diffusion capability.

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4
Q

Plasma membrane structure and function

A

Structure: Has a phospholipid bilayer with proteins

Function: boundary of a cell it maintains the internal environment of a cell by controlling the movement of substances into and out of the cell. It is said to be semipermeable or selectively permeable.

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5
Q

Nucleus structure and function

A

Structure: Contains the genetic material (DNA). It is surrounded by a double membrane known as the nuclear envelope.

Function: Control centre of the cell

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6
Q

What is the cytosol and cytoplasm and their functions

A

Cytosol is the fluid contents only of a eukaryotic cell.

Cytoplasm is the cytosol and all the organelles excluding the nucleus.

Function: Contains dissolved nutrients, helps break down waste products, and moves material around the cell.

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7
Q

Mitochondria function and structure

A

Structure: Is bound by a double membrane and has its own strand of DNA.

Function: The site of cellular respiration (the production of energy as ATP)

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8
Q

Ribosomes structure and function

A

Structure: Are composed of protein and RNA.
Not membrane bound

Function: Is the site of protein synthesis.

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9
Q

Rough endoplasmic reticulum function and structure

A

Structure: is a series of folded membranes studded with ribosomes.

Function: Modifies, folds and transports proteins

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10
Q

Smooth endoplasmic reticulum function and structure

A

Structure: Is series of folded membranes.

Function: Synthesis of lipids

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11
Q

Golgi Complex function and structure

A

Structure: Stack of flattened, membranous sacs.

Function: Stores, modifies and packages proteins for export out of the cell.

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12
Q

Lysosome function and structure

A

Structure: Lipid membrane-bound sac

Function: Is the principal site of digestion within a cell, as they contain digestive enzymes that break down wastes,

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13
Q

Chloroplast function and structure

A

Structure:
Two outer membranes.
Inside the chloroplasts are stacks of flattened sacs or thylakoids which are stacked together as grana.
Contains the green pigment chlorophyll.
Chloroplasts contain some DNA.

Function:The site of photosynthesis

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14
Q

Where are cell walls found and what are they

A

-Are only found in plant, fungi and bacterial cells.
-Are semi-rigid and are a protective barrier.
-Are located outside of the cell membrane.

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15
Q

Vacuole structure and function

A

Structure: isa membrane bound structure found in the cytoplasmic matrix of a cell.

Function: Are the storage container for water, food, enzymes, wastes, pigments and helps plants maintain their shape

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16
Q

What is a cytoskeleton and what does it do

A

Acts as skeleton and muscle and provides shape and structure to the cell.
Helps move organelles around the cell.

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17
Q

What does cellular respiration do

A

Cellular respiration uses glucose and oxygen and produces energy (in the form of ATP), carbon dioxide, and water.

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18
Q

Where does cellular respiration occur

A

Cellular respiration takes place in the cell cytoplasm and the mitochondria.

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19
Q

Cellular respiration formula

A

Glucose + Oxygen ➙ Carbon dioxide + Water + 30/32 ATP
C6H12O6 + 6O2 ➙ 6CO2 +6H2O + 30/32 ATP

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20
Q

Name the 3 major steps of cellular respiration and what happens in each step

A

Glycolysis:
Glucose is broken down into two molecules of pyruvate.

Krebs cycle
Pyruvate is broken down into carbon dioxide and hydrogen

Electron transport chain
The hydrogen ions combine with oxygen to form water

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21
Q

What does photosythesis do

A

Photosynthesis converts sunlight energy into chemical energy.

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22
Q

Name 2 stages of photosythesis and where each stage occurs

A

Light dependant stage - Occurs in the grana
Light independant stage - Occurs in stroma

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23
Q

What happens in light dependant and independant stage of photosythesis

A

Light dependant- light energy is used to split water molecules into hydrogen ions and oxygen molecules

Light independant - hydrogen ions combine with carbon dioxide to form glucose and water.

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24
Q

Describe structure of phosolipid with reference to what is hydrophillic and what is hydrophobic

A

Consists of two fatty acid chains joined to a phosphate-containing group.

Phosphate head - hydrophillic
Fatty acid - hydrophobic

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25
Q

3 types of transport that don’t require energy

A

Simple diffusion
facilitated diffusion
osmosis

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26
Q

2 types of transport that require energy

A

Active transport
Bulk transport

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27
Q

What is diffusion

A

Diffusion is the net movement of a substance, typically in solution, from a region of high concentration of the substance to a region of low concentration across a semi-permeable membrane.

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28
Q

What is facilitated diffusion and where does it occur

A

Facilitated diffusion: the movement of particles from regions of high solute concentration to areas of low solute concentration down a concentration gradient with the aid pf proteins

occurs via:
-Protein channels (always open)
-Protein carriers (will move from outside of membrane to inside with protien)

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29
Q

What is osmosis

A

Osmosis is the diffusion of water from regions of low solute concentration to regions of high solute concentration across a semi-permeable membrane

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30
Q

What is hypotonic

A

having a lower solute concentration than the cell contents
(Water will come into the cell to dilate concentration)

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31
Q

What is hypertonic

A

having a higher solute concentration than the cell contents.
(water will come out of cell to try and dilute)

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32
Q

What is active transport

A

Moves dissolved substances from a region of low concentration to a region of high concentration (against the concentration gradient).

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33
Q

What is bulk transport, what are the 4 types and what do they do

A

Involves transporting solid particles into and out of a cell.

Endocytosis = into a cell.

Phagocytosis = Large molecules

Pinocytosis = Disolved molecules

Exocytosis = transport out of the cells.

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34
Q

Why do eukaryotic cells need to divide

A

growth: during growth period production of new cells is quicker than the death of old ones

replacement and repair: repair and replacement of damaged cells in multicellular organisms.

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35
Q

Binary fission steps

A

1) DNA replicated
2) cell elongates
3) undergoes cytokinesis where the cell is split into two.
4) Two daughter cells are produced.

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36
Q

3 phases of cell cycle

A

Interphase
Mitosis
Cytokinesis

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37
Q

3 stages of interphase and what happens in each

A

1) First gap phase (G1)
The cell increases in size and makes the
mRNA and proteins needed for S phase.

2) Synthesis (S)
The cell duplicates its genetic material
(chromosomes).

3) Second gap phase (G2)
The nucleus is well defined
Rapid cell growth and protein synthesis
The cell prepares for mitosis

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38
Q

Stages of mitosis and what occurs in each

A

Prophase:
DNA condenses into chromosomes
Mitotic spindle forms

Metaphase:
Chromosomes line up on equator of cell

Anaphase:
Chromosomes seperate to opposite poles of cell

Telephase:
Nuclei reform.
Cell elongates and furrow develops.

39
Q

How do animal cells conduct cytokinesis

A

Cleavage furrow

40
Q

How do plant cells conduct cytokinesis

A

Cell plate

41
Q

Compare binary fission and mitosis

A

Binary fission
- faster (relatively)
- simpler (relatively)
- prokaryotes
- no spindle fibres
- no nuclear membrane to break down and reform

Mitosis
- slower (relatively)
- more complex (relatively)
- Eukaryotes
- spindle fibres
- nuclear membrane to break down and reform

42
Q

Name the 3 checkpoints and what each of them check for

A

G1 checkpoint:
* Cell size is large enough.
* Sufficient nutrients are available.
* Signals from other cells have been received.
G2 checkpoint:
* Cell size is large enough.
* Replication of chromosomes has been successfully completed.
* Proteins required for mitosis have been synthesised.
metaphase checkpoint:
* All chromosomes are attached to the mitotic spindle.

43
Q

What is the process of apoptosis

A

The process known as apoptosis or programmed cell death is a genetically controlled and highly regulated process of cell self-destruction

44
Q

What is the intrinsic pathway for apoptosis and when is it used

A

The mitochondrial pathway.The

intrinsic pathway is used when cells come under stress, such as through
infection or damage. When cells are damaged during the cell cycle and the damage
cannot be repaired

Signalled from within the cell

45
Q

What is the Extrinsic pathway and how is it signaled

A

The death receptor pathway.

Another cell signals it

46
Q

4 steps of apoptosis

A
  1. Cell shrinkage
  2. The formation of blebs (protrusions of the cell membrane)
  3. The eventual formation of apoptotic bodies
  4. The clean-up of apoptotic bodies through phagocytosis (after apoptosis).
47
Q

What is necrosis

A

unplanned cell death such as that occurring when cells suffer trauma and die prematurely

48
Q

What is cell differentiation

A

process by which cells become specialised for a specific function

49
Q

Totipotency and where the stem cells are found

A

give rise to all cell types
found in zygotes (Fertilised egg and embryonic cells of a two, four
or eight-cell embryo)

50
Q

Pluripotency and where the stem cells are found

A

differentiate into many cell
types.

Embryonic stem cells from the inner cell mass of the embryonic blastocyst

51
Q

Multipotent and where the stem cells are found

A

differentiate into a closely related family of cells
eg: multipotent blood stem cell can develop into a red blood cell, a white blood cell or platelet

52
Q

Unipotent and where stem cells can be found

A

produce only cells of their own type.
Adult (somatic) muscle stem cells

53
Q

3 germ layers and what it may differentiate to form

A

endoderm
is the innermost germ layer.
It differentiates to form:
The liver, pancreas, and most of the digestive tract

mesoderm
is the middle germ layer
Muscles
Circulatory system (heart and blood vessels)
Skeleton

ectoderm
is the outermost germ layer
Nervous system
Epidermis of skin (including hair, sweat glands, and nails)
Cornea and lens of the eye

54
Q

What are epidermal cells with reference to plants

A

Relatively generalised cells with waxy layer on the upper surface
Reduces water loss from the leaf surface

55
Q

What do root hair cells do

A

Very thin cuticle with no waxy layer. High surface area to volume ratio
Facilitates the uptake of water and ions from the soil

56
Q

What do guard cells do

A

Open or close stomata to regulate water loss

57
Q

Vessel Element of xylem function

A

Rigid remains of a dead cell.
No cytoplasm. End walls perforated.
Walls are strengthened with lignin.

Functions:
Rapid conduction of water.
Provides support for the plant

58
Q

What does the xylem do

A

Xylem is the principal water conducting tissue in vascular plants
Transports water up the plant

59
Q

function of digestive system

A

breakdown of food, digestion of food, absorption of nutrients of food and elimination of undigested material

60
Q

3 organs in digestive system and what they are used for

A

Mouth: mechanical digestion, teeth grind up food

Stomach: connects oesphagus to duodeuem. Acts as a mixing area for food, mixes acids, protein digesting enzymes pepsin into bolus/chyme

small intestine: Lined with villi.Absorb nutrient molecules into blood

61
Q

Function of endocrine system

A

coordinating and controlling body processes

62
Q

3 endocrine glands

A

Thyroid gland
hypothalamus
pituitary gland
Pancreas

63
Q

What are enzymes

A

Enzymes are biological catylist. Have specific regions where the substrate binds called ACTIVE SITE

64
Q

Compare mechanical and chemical digestion

A

Mechanical digestion involves physically breaking down food substances into smaller particles to more efficiently undergo chemical digestion. The role of chemical digestion is to further degrade the molecular structure of the ingested compounds by digestive enzymes into a form that is absorbable into the bloodstream

65
Q

What are Villi and microvilli and what do they do

A

Villi are finger-like projections which are richly supplied with blood vessels. They are present in the inner lining of the small intestine

Provide surface area for absorbing nutrients
Lined with epithelial cells which contain microvilli
Enzymes bound to surface of epithelial cells break down carbohydrates and peptides

66
Q

What do salivary glands produce and what does it break down

A

Amalyase: Breaks down starch

67
Q

What does pepsin do

A

Pepsin is a stomach enzyme that serves to digest proteins found in ingested food.

68
Q

Enzymes are made of____

A

protiens

69
Q

Compare exergonic and endergonic reactions

A

Exergonic = a reaction that results in the net release of energy (breaking down substance usally)

Endergonic = a reaction that requires an input of energy (creating new substance)

70
Q

Protien and steriod hormones: which are hydrophillic and phobic

A

Protein = hydrophilic: cannot diffuse across plasma membrane therefore complimenotry receptors are on membrane

Steriod = Hydrophobic: can diffuse across membrane therefore complimentary receptors are in the cytosol/nucleus

71
Q

Homeostasis definition

A

is maintaining a relatively stable internal
environment within narrow limits.

72
Q

function of excretory system

A

removal of nitrogenous wastes and compounds in excess from the body

73
Q

3 main organs of excretory system

A

liver
kidney
bladder

74
Q

Nephron structure and what each part does

A

1) Bowmans capsule and glomerulus: Filters small solutes from blood (forms filtrate)
2) Proximal convoluted tubule:
reabsorbs ions, water and nutrients; removes toxins and adjusts ph of filtrate
3) decending loop of henle: Water is reabsorbed
4) acending loop of henle: Ions are reabsorbed
5) distal tubule: selectivity secretes and re absorbs different ions to maintain blood Ph and electrolytes
6) Collecting duct: reabsorbs solutes and water from filtrate

75
Q

what is negative feedback

A

The stimulus from one part of the body
produces a response that will stop or
reduce the original stimulus

76
Q

what is positive feedback

A

The stimulus from one part of the
body will cause another part to
enhance the effect of stimulus.

77
Q

Ectothermic and Endothermic

A

ectothermic= Depend on external sources of heat to generate their body warmth

endothermic = have an in-built source of body heat

78
Q

Stimulus response model for an decrease in blood glucose

A

1) Stimulus: decrease in blood glucose
2)Alpha cells of pancreas
3) Modulator: Alpha cells of pancreas secrete glucagon
4) effectors: Liver cells
5) Response: Increase of blood glucose by release of glucose into the blood from liver

79
Q

Stimulus response model for an Increase in blood glucose

A

1) Stimulus: Increase in blood glucose
2)Beta cells of pancreas
3) Modulator: beta cells of pancreas secrete insulin
4) effectors: skeletal muscle
5) Response: Decrease of blood glucose by uptake from muscle

80
Q

Stimulus response model for a drop in temperature

A

1) Stimulus: Decrease in body temperature below normal
2) Decrease detected by thermoreceptors in skin, organs or hypothalmus
3) Modulator: Hypothalmus sends signals via nerve and hormonal systems
4) effectors: Blood vessels or Skeletal muscles
5) Response: Reduced bloodflow in skin vessels (vasoconstriction) or Shivering

81
Q

Stimulus response model for an increase in temperature

A

1) Stimulus: Increase in body temperature below normal
2) Increase detected by thermoreceptors in skin, organs or hypothalmus
3) Modulator: Hypothalmus sends signals via nerve and hormonal systems
4) effectors: Blood vessels or Sweat Glands
5) Response: Increased bloodflow in skin vessels (vasodilation) or Sweating

82
Q

Stimulus response model for an decrease in water balance

A

1) Stimulus: decrease in water balance
2) Decrease detected by osmoreceptors
3) Modulator: Hypothalmus signals ADH release
4) effectors: Kidney collecting ducts
5) Response: Kidney collecting ducts become more permable to water and therefore there is increases reabsorption

83
Q

Stimulus response model for an decrease in water balance

A

1) Stimulus: increase in water balance
2) osmoreceptors are silent
3) Modulator: Hypothalmus signals ADH release
4) effectors: Kidney collecting ducts
5) Response: Kidney collecting ducts become more permable to water and therefore there is increases reabsorption

84
Q

draw a fluid mosiac model that contains glycolipids, protiens and gycoprotiens

A

look at diagram in slideshows

85
Q

4 things that living things have

A
  • ribosomes
  • Genetic material
  • Plasma membrane
  • Cytosol
86
Q

draw and label a diagram of apoptois

A

look at diagram in slideshows

87
Q

what is a result of too little or too many apoptois

A

too much - alziehmers
too little - cancerous cells

88
Q

3 types of stem cells, their potency and advantage and disadavantge

A

Embryonic stem cells: embryo up until 12 cells
Toti or pluri potent
advantage: can turn into most/all cells
Disadvantage: ethical considerations (killing)

Somatic stem cells: anything bast a embryo until death
Multipotent or uni potent
Advantage: No ethical concerns
Disadvantage: Can only turn into a few types of cells

Induced pluripotent stem cells: Somatic cells that have been induced back to pluripotent
Advantage: No ethical concerns and can turn into most/all cells
Disadvantage: Not sure how to do it yet

89
Q

Phloem function

A

transports sugars and minerals down and around the plant
Have a Sieve tube element

90
Q

Transpiration pull

A

Water is lost from the air spaces by
evaporation through stomata and is
replaced by water from the mesophyll cells. The constant loss of water to the air, together with production of sugars, creates
a solute concentration in the leaves that is higher than elsewhere in the plant. Water is pulled through the plant along a gradient of
increasing solute concentration

91
Q

What is going in and out when stomata are open/closed

A

When stomata is open water is exiting but carbon dioxide is entering therfore photosythesis can take place

When stomata is closed then water is not lost but carbon dioxide cannot enter

92
Q

Cohesion tension

A

The transpiration pull is assisted by the special cohesive properties of water. Water molecules cling together as they are pulled
through the plant. They also adhere to the walls of the xylem (adhesion). This creates one unbroken column of water through the plant. The upward pull on the cohesive sap creates a tension (a negative pressure). This helps water uptake and movement up the plant

93
Q

Root pressure

A

Water entering the stele from the soil creates a root pressure. This is a weak ‘push’ effect. for the water’s upward movement through the
plant. Root pressure can force water droplets from some small plants under certain conditions (guttation), but generally it plays a minor part in the ascent of water

94
Q
A

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