specialised cells Flashcards

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1
Q

define ‘totipotent cell’

A

undifferentiated stem cell with potential to become a whole organism

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2
Q

define ‘pluripotent cell’

A

-stem cells which have started to differentiate but still have the potential to become any of the different types of tissue within the organism
- by differentiating they have lost the ability to form the extra-fetal tissues so can’t become the whole organism

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3
Q

define ‘multipotent cell’

A

stem cells which have differentiated to the point where they can only form a range of cells within a certain type of tissue

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4
Q

describe each stage after fertilisation

A
  1. A zygote is formed which begins to divide by mitosis
  2. 2 cell stage - blastomere
  3. 4 cell stage - zona pelucida (jelly coat of egg)
  4. 8 cell stage
  5. Morula - stem cells are totipotent
  6. Early blastocyst - differentiation has occurred - inner cell mass stem cells become embryo - outside stem cells become the placenta
  7. Late blastocyst - stem cells now pluripotent
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5
Q

describe the adaptation properties of an erythrocyte

A
  • disc shaped to create high surface area to volume ratio
  • all haemoglobin molecules near surface for diffusion of oxygen
  • biconcave shape to create large surface area and some flexibility when moving through narrow capillaries
  • greater thickness around edge allows for more haemoglobin
  • nucleus and other organelles are lost to increase volume available
  • packed with haemoglobin which has an affinity for oxygen and carries it to respiring tissues
  • all of these adaptations helps the red blood cell to transport oxygen
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6
Q

Describe and explain the specialisation and function of the animal cell ‘neutrophils’

A
  • many lysosomes so ingested particles can be broken down
  • lots of ribosomes and RER needed to make proteins
  • golgi required for making the lysosomes + packing enzymes into vesicles
  • lots of mitochondria so sufficient aerobic respiration can take place to make enough ATP to provide energy for all anabolic processes
  • plasma membrane has receptors to detect foreign antigens
  • nucleus in lobes so more flexible
  • all of these adaptations help the cell to carry out its function of phagocytosis
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7
Q

Describe and explain the specialisation and function of the animal cell ‘spermatozoa’ (sperm cells)

A
  • haploid nucleus
  • flagellum made of microtubules for locomotion and motile movement (swim independently)
  • many mitochondria to do aerobic respiration to produce enough ATP to supply energy required for swim
  • acrosome (specialised lysosome) ruptures allowing for the enzymes to be released and penetrate through egg’s jelly coating
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8
Q

Describe and explain the specialisation and function of the plant cell ‘palisade mesophyll’

A
  • contain many chloroplast which can move along cytoskeleton tracks towards a light source
  • chloroplast pushed close to cellulose cell walls by turgor pressure exerted by vacuole
  • thin cellulose cell walls so short diffusion distance pathway for co2 for photosynthesis
  • tightly packed together and ability to move in palisade mesophyll tissue so there’s a high concentration of chloroplast where light is available
  • specialised for photosynthesis
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9
Q

Describe and explain the specialisation and function of the plant cell ‘root hair cell’

A
  • found on outer surface of roots with hair like projections protruding the soil
  • shape gently increases surface area of the cell for uptake of water and minerals from soil
  • cell wall is fully permeable and contains lots of intrinsic proteins for transport of polar molecules
  • some will be actively transported so many mitochondria present so ATP can be made to drive import of polar molecules against concentration gradient
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10
Q

Describe and explain the specialisation and function of the plant cell ‘guard cell’

A
  • two guard cells surround each stoma (mostly found on underside of leaf)
    has exchange takes place through stomata including uptake of co2 from atmosphere for photosynthesis
  • when water vapour exits, function of guard cells is to open stomata to allow in co2 when light is available but to avoid water loss when dark
  • guard cells contain chloroplast so when light is available it’s absorbed and photosynthesis can occur
  • ATP used to actively pump ions into the guard cells to lower water potential so water moves in from surrounding cells
  • cellulose cell wall is thinner on outside and thicker on inside edge so when cell becomes turgid the cell distorts its shape because of the unevenness and opens the stomata.
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11
Q

what is meant by ‘tissue’

A

-a collection of differentiated cells that are similar and work together to carry out a function

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12
Q

What is a nervous tissue?

A

Sensory neurones, relay neurones and motor neurones all work together to transmit nervous impulses

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13
Q

Explain why blood is a tissue

A

-all of the cells (red and white blood cells, platelets) have the same origin

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14
Q

Describe and explain the function/ location of the specialised animal tissue ‘simple squamous’.

A
  • epithelial tissue = covers body surfaces
  • simple epithelial = one cell thick
  • squamous epithelial = flattened in shape to reduce diffusion pathway for gas exchange.
  • it forms the walls of the alveoli and capillaries to allow rapid diffusion of oxygen from the air into the blood
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15
Q

Describe and explain the function/ location of the specialised animal tissue ‘ciliated epithelium’

A
  • columnar epithelial tissue that’s ciliated
  • ciliated epithelial and goblet cells are found lining the trachea
  • they work together to keep the lungs clean
  • goblet cells secrete the mucus which traps any dirt, dust, pollen, bacteria
  • the cilia then move in a rhythmic pattern to waft the mucus up and away from the lungs
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16
Q

Describe and explain the function/ location of the specialised animal tissue ‘cartilage’

A
  • a firm but flexible connective tissue composed of chondrocyte cells embedded in an extracellular matrix
  • forms the scaffolding of the nose and outer ear
  • covers the end of bones with joints to prevent the bones from rubbing together
17
Q

Describe and explain the function/ location of the specialised animal tissue ‘muscle’

A
  • skeletal muscle is able to contract (shorten in length) so that bones are pulled in a new position during locomotion
  • has a highly developed cytoskeleton and the myofibrils form the dark pink bands
  • the muscle fibres are separated by connective tissue which forms the white strips
18
Q

Describe and explain the function/ location of the specialised plant tissue ‘epidermis’.

A
  • single layer of closely packed cells
  • cover upper and lower surfaces of the leaf
  • they are transparent with no chloroplast to allow light transmission to photosynthesising cells
  • epidermis usually covered by a waxy cuticle which waterproofs the leaves surface to keep water inside the cell
19
Q

Describe and explain the function/ location of the specialised plant tissue ‘xylem’

A
  • thick, strong cell walls containing cellulose and lignin to support the plant
  • join end to end to form long continuous tubes
  • they are dead and have no cytoplasm so space inside can be used to transport water and minerals
20
Q

Describe and explain the function/ location of the specialised plant tissue ‘phloem’

A
  • sieve tube cells are connected to each other through sieve plates that have many pores allowing sugars to be transported
  • sieve tubes have modified cytoplasm with few organelles so tube can transport sugar
  • sugar transport in sieve tubes requires energy from the plant
  • companion cells involved in this process
21
Q

What is an organ?

A

A collection of different tissues working together to perform a particular function.

22
Q

What is an organ system?

A

Made up of a number of organs working together to perform an overall function.

23
Q

Explain how the leaf is an organ in a plant.

A
  • tightly packed palisade mesophyll tissue near top of leaf for efficient light absorption and mobile chloroplasts which can move nearer the light source for max light absorbance efficiency
  • many airspaces between irregularly shaped spongy mesophyll cells speed up rate of diffusion
  • upper epidermis is transparent and lies horizontally to enhance light transmission
  • waxy cuticle is waterproof to avoid excess evaporation of water