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Biology Paper 1 > Cells and Control > Flashcards

Cells and Control Flashcards

1
Q

what does the nucleus contain?

A

genetic material in form of chromosomes

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2
Q

define diploid

A

two copies of each chromosome (46)

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3
Q

define haploid

A

half the number of chromosomes (23)

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4
Q

what’s a cell cycle?

A

lifecycle of a cell involving cell growth, DNA replication and cell division

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5
Q

describe the stages of mitosis.

A
  1. interphase : sub cellular structures increase in size, DNA is replicated (forms X shape) and energy stores are increased
  2. PROPHASE : chromosomes condense and membrane around nucleus break down
  3. METAPHASE : chromosomes line up in the middle of the spindle fibers
  4. ANAPHASE : cell fibres pulled apart of each arm of the DNA goes to the opposite sides of the cell
  5. TELOPHASE : membranes form around each set of chromosomes to become nuclei
  6. CYTOKINESIS : cytoplasm and cell membrane divide to form two identical daughter cells
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6
Q

why is mitosis important in organisms?

A
  • asexual reproduction
  • growth
  • repair of damaged cells
  • cell replacement
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7
Q

what does mitosis produce?

A
  • two genetically identical diploid daughter cells
  • used for somatic cells
  • identical set of chromosomes as parents
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8
Q

what’s mitotic index?

A

how many cells are involved in mitosis (prophase - telophase )

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9
Q

a cell divides by mitosis every 2 minutes. calculate the number of identical cells present after 10 minutes.

A

10/2 =5
2^5 = 32 cells

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10
Q

define growth

A

increase in size/mass

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11
Q

describe growth in animals.

A
  • when young, cells divide at a fast rate. animals reach the full growth and stop and cell division is only required to repair/replace damaged cells.
  • most cells differentiate in early stages and become specialized. specialized cells can produce more through mitosis. some adult stem cells retain ability to differentiate
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12
Q

describe growth in plants

A
  • cell division occurs in the meristem and rate stays the same as long as the plant lives
  • cell elongation occurs in all cells as they expand and enable growth of plant
  • meristem stem cells can differentiate into any cell type for as long as the plant lives
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13
Q

what is cancer?

A
  • a change in genes controlling cell division has a change which results in uncontrollable cell division
  • mass abnormal cells forms primary tumor
  • as tumor invades and destroys other surroundings it forms secondary tumors - what we call cancer
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14
Q

what are percentile charts?

A

chart used to assess baby’s growth overtime
- measures mass, length and head circumference

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15
Q

what can a doctor determine from percentile charts?

A
  • slower growth than normal (below the bottom line)
  • faster growth than normal (above top line)
  • abnormal growth (irregular growth patterns)
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16
Q

what does the 50th percentile mean?

A

baby is bigger than 50% of babies

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17
Q

what are stem cells?

A

undifferentiated cell which can undergo cell division and later differentiate

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18
Q

why is cell differentiation important?

A

enables formation of specialised tissues with specific functions

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19
Q

explain what are embryonic stem cells

A

form when egg and sperm cell fuse to produce zygote
- can differentiate into any kind of cell
- can clone these and direct into any part of body ( used for replacing insulin producing cells for diabetics)

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20
Q

explain what are adult stem cells

A
  • found in bone marrow
  • can only produce certain type of cells
  • in animals, can be used to produce damaged cells
  • used to cure some diseases ex. sickly anemia
21
Q

where are meristem tissues found?

A

in roots and shoot tips

22
Q

what are meristem cels found in plants

A
  • produce unspecialised cells that differentiate into any type of cell throughout the life of the pant
  • can be used to produce clones of plants
23
Q

how can stem cells be used in medicine?

A
  • differentiate into specific cell types
    -specialised cells can be transplanted into patient
  • used to treat DAMAGE or disease
24
Q

describe theraputic cloning

A
  • an embryo with sane genes as patient are produced
  • harvested to obtain embyronic stem cells
  • grow into any cell needed to replace the damaged ones
  • not rejected as they have the same exact genetic material as patient
25
Q

what are benefits of stem cell resarch

A
  • used to replace damaged/ diseased body parts
  • unwanted fertility clinics can be used instead of discarded
  • research process of cell differentiation
26
Q

what are problems of stem cell research?

A
  • tumor development -unable to control rate at which transplanted cells divide in patient so tumor cells can develop
  • disease transmission - if donor stem cells are contiminated with virus this can be passed onto patient
  • rejection : patients body recognise foreign cells and trigger immune system. can take drugs but this leaves them susceptible to other diseases
  • ethical issues - interference with natural production of life
27
Q

describe the function and structure of the brain.

A
  • cerebrum : divided into cerebral hemispheres which controls opposite sided of body. function - movement, intelligencence, sensory processing
  • cerebellum : controls fine movement of muscles and coordination
  • medulla oblagants : found in brainstem, carries out automatic function
28
Q

what’s the spinal cord and function?

A

a long thin structure composed of neurones that extends from medulla down spine
- connections PNS to brain

29
Q

what’s a CT Scan and how are they useful in investigating brain function?

A
  • XRAY at brain in several angles to generate 3D image of brain
  • shows structure of brain
  • can show damaged/diseased areas of the brain which can be used to find the function
  • exposes patient to high concentration of radiation
30
Q

what’s a PET scan and how are they useful in investigating brain structure?

A
  • inject radioactive tracer into blood to show areas with greater blood flow are active
  • can study disorders that change brain activity and identify cancer tumors
  • very detailed - can investigate structure and function of brain by comparing with healthy patients
31
Q

why is it difficult to treat damage to CNS?

A
  • hard to repair damage on nervous system : neurones cannot repair themselves and can be easily damaged
  • not easy to access - drugs used to treat brain cannot reach membrane surrounding it
  • treatment coule lead to further damage - if spinal cord needs surgery they can be damaged during operation
  • tumors can push against other structures ofbrain vessels which restrict their function and is difficult to remove as they’re very deep
32
Q

how does the CNS coordinate a response to the stimulus?

A
  • stimulus is detected by receptor and converted to eletrical impulse
  • travels along sensory neurone to CNS
  • information is processed and reponse is sent as electrical impulse along motor neurone to effector
  • effector carries out appropriate response
33
Q

what are adaptations of nerve cells?

A
  • myelin sheath : surrounds axon acting as an electrical insulator which speeds up electrical impulse
  • long : speeds up impulse
  • axon : carries nerve impulses towards body
34
Q

describe structure and function of motor neurone

A
35
Q

describe structure and function of motor neurone

A
36
Q

describe structure and function of motor neurone

A
37
Q

what’s a synapse?

A

gap between two neurones

38
Q

describe how nerve impulses are transmitted across synapse.

A
  1. nerve impulse reaches presynaptic neuron, which triggers release of neurotransmitters
  2. the neurotransmitters are diffused across synaptic gap
    - reaches 2nd neuron which triggers a new electrical impulse
    - transmission of nerve impulse is very fast but slowed at synapse as diffusion takes time
39
Q

what is a reflex

A

an automatic response to stimuli which is involuntary to prevent harm of body
- neurones go through unconscious åart of brain unlike usual cns response to stimuli

40
Q

describe reflex arc

A
  1. stimulus is detected by receptor
  2. when impulse reaches synapse of sensory and relay neurotransmitters are released which causes impulse to be sent along relay
  3. impulse is carried along motor to effector
  4. this results in appropriate response
41
Q

describe functions of different parts of eye

A
  • cornea : allows light through and retracts onto retina
  • iris : controls how much light goes into light
    - in dim light, pupil is larger -> more light
    enters
    - in bright light, pupil smaller -> less light
    enters to avoid damage to retina
  • retina : light sensitive area covered with receptor cells
    - cone cells > detect light colour > works best in bright light
    - rod cells > detect light intensity > works best in dim light
  • ciliary and suspensory ligaments : holds lens in place
  • lens : transparent curved surface of eye
  • optic nerve : carries electrical impulse > brain
42
Q

what’s accomdation?

A

eyes can focus light onto retina by changing shape of lens

43
Q

describe how the eye focuses on near objects

A
  • ciliary muscles contract & suspensory ligaments relax
  • lens becomes more curved and thicker > refracts light more
44
Q

describe how eye focuses on distant objects

A
  • cililary musle relax & suspensory contract
  • lens becomes less curved and thinner > refracts less light
45
Q

what is long sightedness ?

A
  • unable to focus on nearby objects
  • lens is too thin/eyeball is too short > doesnt refract enough light
  • light from near objecfts are bought focus behind retina
  • use glasses / contacts with CONVEX lens
46
Q

what is short sightedness?

A
  • unable to focus on distant objects
  • lens is too curved/ eyeball too long > refracts too much light
  • light from distant objects is brought to focus in front of the retina
  • use glasses / contacts with CONCAVE lens
47
Q

what is colour blindness?

A

inability to tell difference between certain colours
- occurs when there’s not enough cone cells in retina due to genetics

48
Q

what is cataracts and how can it be corrected?

A
  • cloudy patch on eye which restricts vision and colours look less vivid
  • treated by replacing with artificial lens

Biology Paper 1 (5 decks)

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