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A-level Biology > Module 2 > Flashcards

Module 2 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Eukaryotic cell

A

Animal/ plant cell has membrane bound organelles ( eg nucleus, rer, Golgi )

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2
Q

Prokaryotic cells

A

Bacteria, has no membrane bound organelles

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3
Q

Sexual reproduction

A

In animal and some plants. Uses 2 parents( each provides a gamete which fusses to form a zygote, zygote develops into organism

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4
Q

Asexual reproduction

A

In microorganisms and some plants. Uses 1 parent to produce genetically identical offspring

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5
Q

How does a zygote develop into an organism

A

Zygote is a stem cell
Zygote divides by mitosis to make many stem cells
Each stem cel differentiates into specialised cell
Each specialised cell divides by mitosis to make many copies and form a tissue.
Different tissues join to form an organ, different organs join to form an organ system. This is surrounded by the body

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6
Q

Stem cell

A

Undifferentiated/unspecialised cell, can form any type of cell

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7
Q

Tissue

A

A group of specialised cells

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8
Q

Organ

A

Made of different tissues

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9
Q

Organ system

A

Different organs working together

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10
Q

Do ribosomes have a membrane

A

No

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11
Q

Structure of nucleus

A

Contains dna ( made of genes, genes code for making proteins).
Dna wrapped around histones to form chromatin
Double membrane, called nuclear envelope, which contains pores
At centre there’s nucleolus- produces mRNA
Rest of nucleus made of nucleoplasm( contains the dna/chromatin

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12
Q

Structure of chloroplast

A

Organelle for photosynthesis, double membrane, discs called thylakoids, thylakoids contain chlorophyll, stack of thylakoids called granum, thylakoids surrounded by fluid called stroma

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13
Q

Vacuole

A

Surrounded by a membrane called a tonoplast, contains cell sap ( water,sugar,minerals)

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14
Q

What’s bacteria made of

A

No nucleus so loose dna in form of single loop plasmids.
No membrane bound organelles
Cytoplasm
Cell membrane and cell wall ( made of murein/ peptidoglycan)
Some have a capsule and flagella

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15
Q

What is a virus made of

A

DNA or rna( if rna, it contains reverse transcriptase to turn rna into dna )
Protein coat called capsid and lipid coat
Attachment proteins on outside

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16
Q

How do viruses infect host cells

A

Infect host cells by attaching using their attachment protein, send in their dna which uses the cell to make the viruses components and uses the cell membrane to make the viruses lipid coat, hence, producing copies of the virus and destroying the host cell

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17
Q

What is a chromosome

A

DNA coiled form
Formed during interphase of cell division( mitosis/meiosis)in animal/plants
Made of 2 identical/sister chromatids joined by a centromere
Carries 2 copies of the same dna molecule

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18
Q

What’s a homologous pair of chromosomes

A

A pair of chromosomes ( 1 from mother the other from father)
Carries same genes but different alleles - there are 23 pairs in humans

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19
Q

Mitosis definition

A

Produces genetically identical cells for growth and repair of tissues

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20
Q

Meiosis definition

A

Produces genetically different haploid cells as gametes for sexual reproduction

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21
Q

Prophase

A

DNA coils to form chromosomes, nucleus breakdown, spindle fibre’s form

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22
Q

Metaphase

A

Chromosomes line up in middles of cell and attach to spindle fibres via centromere

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23
Q

Anaphase

A

Spindle Fibres pull, centromere splits, sister chromatids move to opposite sides

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24
Q

Telophase

A

Chromatids uncoil, nucleus reforms ( left with 2 genetically identical nuclei )

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25
Q

Cytokinesis

A

Separating into 2 cells

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26
Q

What happens to mass in mitosis

A

Halves

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27
Q

What happens to chromosomes number in mitosis

A

Stays the same ( diploid )

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28
Q

What does meiosis produce

A

4 genetically different cells, haploid ( half the amount of chromosomes/dna)

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29
Q

Meiosis 1- prophase

A

DNA coils to form chromosomes, nucleus breaks down, spindle fibres form
Crossing. Over occurs

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30
Q

Meiosis 1 - metaphase

A

Homologous pair of chromosomes line up in middle of cell and attach spindle fibres via centromere by random assortment

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31
Q

Meiosis 1 - anaphase

A

Spindle fibres pull, homologous pair of chromosomes separate to opposite sides by independent segregation

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32
Q

Meiosis 1 - telophase

A

Chromosomes uncoil, nucleus reforms ( left with 2 nuclei )

33
Q

Meiosis 11- prophase

A

DNA coils to form chromosomes, nucleus breaks down , spindle fibres form

34
Q

Meiosis 11- metaphase

A

Chromosomes line up in middle of cell and attach to spindle fibre via centromere by random assortment

35
Q

Meiosis 11- anaphase

A

Spindle fibres pull, centromere splits , sister chromatids move to opposite sides by independent segregation

36
Q

Meiosis 11- telophase

A

Chromatids uncoil, nucleus reforms ( left with 4 genetically different nuclei )

37
Q

How does meiosis produce variation

A

Crossing over and independent segregation

38
Q

What’s independent segregation

A

In anaphase 1 and meiosis 1 - the homologous pairs of chromosomes separate
In anaphase 11 and meiosis 11- the chromatids separate
Independent segregation produces a mis of alleles from paternal and maternal chromosomes in gametes

39
Q

What’s crossing over

A

Occurs in prophase 1 of meiosis 1
Homologous pairs of chromosomes wrap around each other and swap equivalent sections of chromatids- produces new combinations of alleles

40
Q

How do bacteria do cell division

A

Binary fission
Copy their dna ( single loop and plasmids ) and then separte into 2 new genetically identical bacteria ( asexual reproductive)

41
Q

2 types of microscopes

A

Light and electron( transmit ion and scanning )

42
Q

Magnification

A

How much larger the image side is compared to the actual size
Magnification = image size /actual size

43
Q

Which microscope has higher magnification

A

TEM > SEM > LM

44
Q

Which microscope has higher resolution

A

TEM > SEM > LM

45
Q

Advantages / disadvantage of SEM

A

produces 3D image
Only works in a vacuum so can only observe dead specimens, black and white image
, artefacts

46
Q

Simple diffusion

A

Molecules move directly through the phospholipid bilayer

47
Q

Facilitated diffusion

A

Molecules pass through transport proteins ( large use carrier, charged use channel)

48
Q

Factors that affects rate of diffusion

A 
Surface area ( increase = increase rate of diffusion ) 
Concentration gradient ( increase = increase diffusion )
Thickness ( decreases= decrease in diffusion distance = increase diffusion)
Temperature ( increase = increase kinetic energy = molecules move faster = increase rate of diffusion)
Size of molecule ( smaller molecules = increase rate of diffusion )
49
Q

What’s ficks law

A

( Surface area x conc gradient) / Thickness

50
Q

What happens if you surround animal cell with pure water

A

Swells and bursts ( water enter via osmos )

51
Q

What happens when you surround plant cells with pure water

A

Swells but does not burst
Cell wall prevents it from bursting , made of cellulose - strong material
The cells is turgid

52
Q

What happens when you surround animal cell with conc sugar/salt solution

A

Shrinks ( water leaves by osmosis )

53
Q

What happens when you surround plant cell with conc sugar/salt solution

A

Water leaves via osmosis
Cell wall prevents cell from shrinking, keeps it rigid
The protoplast ( cell membrane plus contents ) shrink
The cell is plasmolysed

54
Q

Describe process of active transport

A

Molecules ( in low conc) bind to carrrier protein
ATP breakdown down to adp, pi and energy ,
the pi and energy cause carrier protein to change shape
Carrier proteins release molecules on opposite side ( in area of high conc )
The carrier protein releases the attached pic to return to its original shape

55
Q

Enzymes of protein digestion

A

Endopeptidase( in stomach ), hydrolyses peptide bonds in middle of polypeptide chain into many smaller chains
Exopeptidase( in small intestines ) hydrolyses peptide bonds at end of chains to leave dipeptides
Deipeptidase ( on lining of SI ) hydrolyse dipeptides into amino acids

56
Q

Enzymes of lipid digestion

A

Lipase in small intestine leaves monoglycerides and 2 fatty acids

57
Q

Adaptions of SI for absorption

A

Folded to form villus ( large SA)
cells lining SI have microvilli. ( large SA )
wall of SI is thin ( short diffusion pathway)
Rich blood supply ( maintains conc gradient )

58
Q

What’s a pathogen

A

A disease causing micro-organism , eg bacteria, virus , fungi
Bacteria cause disease by producing toxins
Virus causes disease by producing toxins
Virus cause disease by dividing in cells causing them to burst

59
Q

Body defences against pathogens

A

Barriers - prevents pathogens entering the body
Phagocytes - perform phagocytosis and stimulate specific response
Specific response - uses lymphocytes to produce memory cells and antibodies

60
Q

What are the barriers against pathogens

A

Skin- an impermeable barrier made of keratin
Cilia and mucus in lungs
Stomach acid - denatures / breakdown pathogens

61
Q

Describe the process of phagocytosis

A

Pathogen releases chemicals, this attracts the phagocyte, the phagocyte binds to the pathogen and engulfs it , forms a phagosome around pathogen , Lysosomes inside the phagocyte releases digestive enzymes into the phagosome , breaking down the pathogen by hydrolysis

62
Q

Describe the specific response

A

Phagocytes perform phagocytosis without destroying the antigen, they place antigens on their surface, presenting the. T cells bind to the antigen and become stimulated , they divide by mitosis to form 3 types of cells ( t helper , t killer and t memory )
T helper stimulate B cells , t killer kill infected cells , t memory provide long term immunity

63
Q

B cells

A

Engulf and present antigens on their surface, the t helper cells bind to this
The B cells become stimulated and divide by mitosis to make plasm cells and b memory cells.
Plasma cells make antibodies
B memory cells provide long term immunity

64
Q

What is an antigen

A

A protein on the surface of a pathogen that stimulates an immune response

65
Q

What is an antibody

A

A globular protein, made by plasma cells , has 3 regions

66
Q

Variable region on an antibody

A

Has a different shape in each antibody, contains the antigen binding sites, these bind to complimentary antigens ( on a pathogen ) to form an antigen- antibody complex , destroying the pathogen

67
Q

Hinge region on an antibody

A

Gives the antibody flexibility

68
Q

Constant region on an antibody

A

The same shoe in all antibodies, binds to phagocytes to help with phagocytosis

69
Q

Active immunity

A

Individual has memory cells - can make their own antibodies and provides long term immunity

70
Q

Passive immunity

A

Person given antibodies, these work then die, no long term immunity, so no memory cells

71
Q

How does active immunity occur

A 
Naturally= by primary infection 
Artificially = by vaccination
72
Q

How does passive immunity occur

A 
Nationally = from mother to baby ( placenta or breast milk)
Artificially = by injection
73
Q

Successful vaccination programme

A

Produces suitable vaccine ( effective , doesn’t cause disease , no major side effects, low cost, easily produced/transported/stored/administered)
Herd immunity

74
Q

What is herd immunity

A

When a large proportion of the population is vaccinated, therefore most people will be immune, only a few will not be immune, increases chance of non-immune person

75
Q

Problems with vaccination programmes

A 
Vaccine doesn’t work 
Vaccine not safe 
Many strains of pathogens 
Cannot achieve herd immunity 
Antigenic variability
76
Q

What is antigenic variability

A

The pathogen mutates, the antigen changes shape, so the memory cells no longer complimentary- do no recognise the pathogen, therefore the pathogen can re harm

77
Q

What is hiv/ aids

A

HIV = human immunodeficiency virus , AIDS = acquired immunodeficiency syndrome
HIV is the pathogen , AIDS is the infectious disease
HIV is spread by fluid to fluid contact ( unprotected sex, needle , mother to child)

78
Q

What does HIV destroy

A

HIV damages and destroys T helper cells, therefore person no longer produces immune response and has no defence against pathogens/ infections ( AIDS )
Which AIDS individuals at risk from all sorts of pathogens/infections called opportunistic infections

A-level Biology (12 decks)

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