Cell specialisation and stem cells

Question 1

differentiated

Answer 1

specialised to carry out a function

Question 2

specialisations of erythrocytes (3)

Answer 2

• flattened biconcave shape increasing SA:Vol ratio
• no nuclei or many other nuclei to max space for Hb
• flexible so can squeeze through narrow capillaries

Question 3

specialisations of neutrophils (2)

Answer 3

• multi-lobed nucleus so easier to squeeze through small gaps to get to site of infection
• granular cytoplasm contains many lysosomes with enzymes used to digest pathogens

Question 4

specialisations of sperm cells (3)

Answer 4

• tail/ flagellum so can move
• many mitochondria to supply energy to swim
• acrosome at head contains digestive enzymes to digest protective layer around ovum and allow sperm to penetrate and fertilise the egg

Question 5

specialisations of palisade cells (4)

Answer 5

• many chloroplasts to absorb light for photo
• rectangular box shaped so can be closely packed
• thin cell walls to increase r.o.diffusionof CO2
• chloroplasts can move within cytoplasm to absorb more light

Question 6

specialisations of root hair cells (1)

Answer 6

• have root hairs which increase SA to maximise uptake of water and minerals from soil

Question 7

specialisations of guard cells (2)

Answer 7

• when they lose water they become flaccid and stomata close to prevent further loss of water
• cell wall thicker on one side so cell does not change shape symmetrically as its volume changes

Question 8

specialisations of squamous epithelium (1)

Answer 8

• made up of very thin epithelial cells which allow rapid diffusion across the surface. (essential as forms lining of lungs and allows rapid diffusion of O2 into blood)

Question 9

specialisations of ciliated epithelium (2)

Answer 9

• cilia move in rhythmic manner and sweep mucus away from the lungs in trachea
• goblet cells release mucus which trap dust and dirt particles (pathogens)

Question 10

specialisations of cartilage (connective tissue found in outer ear, nose, and between bones. Contains elastin and collagen)

Answer 10

• chondrocyte cells embedded in extracellular matrix. Prevents bones rubbing together and causing damage.
  Firm flexible connective tissue

Question 11

specialisations of muscle

Answer 11

skeletal muscle fibres contain myofibrils which contain contractile proteins that allow the muscle to contract (shorten) and move bone

Question 12

specialisations of epidermis tissue

Answer 12

• covered by waxy cuticle to reduce water loss

- contains stomata which can open and close to allow CO2, O2 and water vapour in and out

Question 13

specialisations of xylem tissue

Answer 13

• elongated dead vessel elements allow water and minerals to travel up in continuous stream
• xylem walls strengthened with waterproof lignin, which provides the plant with structural support

Question 14

specialisations of phloem tissue

Answer 14

• sieve tube elements perforated by sieve plates

- companion cells are very metabolically active and provide phloem with necessary support

Question 15

potency

Answer 15

the ability of a stem cell to differentiate into different cell types

Question 16

totipotent

Answer 16

stem cells that can different into any type of cell

• fertilised egg (zygote)
• 8 or 16 cells from first few mitotic divisions

Question 17

pluripotent

Answer 17

stem cells that can form all tissue types but not whole organisms
- early embryos

Question 18

multipotent

Answer 18

stem cells that can only form a range of cells within a certain type of tissue
- haematopoetic stem cells in bone marrow can make different types of blood cell