Paper 2 SL

discuss possible exceptions to cell theory

• skeletal muscle fibers are larger/have many nuclei / are not typical cells

• fungal hyphae are (sometimes) not divided up into individual cells

• unicellular organisms can be considered acellular because they are larger than a typical cell / carry out all functions of life

• some tissues / organs contain large amounts of extracellular material

  • vitreous humor of eye / mineral deposits in bone / xylem in trees / other example

ovary: produces

eukaryotic cells have intracellular and extracellular components

state the functions of one names extracellular component

• plant cell wall / cellulose / interstitial

• prevents the entry of pathogens

• maintains the shape of plant cells

• prevents excessive entry of water to the cell

explain how the surface area to volume ratio influences cell sizes

• small cells have larger ratio (than larger cells) / ratio decreases as size increases

• surface area / membrane must be large enough to absorb nutrients / oxygen / substances needed

• cell size is limited (by SA / Volume ratio) / cells divide when they reach a certain size

outline differentiation of cells in a multicellular organism

• differentiation is development in different / specific ways

• cells carry out specialized functions / become specialized

• each cell contains all the genetic information for the production of the complete organism

• each cell becomes a specific type of cell dependent on which DNA segment becomes active

describe the importance of stem cells in differentiation

• stem cells are undifferentiated cells

• stem cells can differentiate in many / all ways = are pluripotent / totipotent

• differentiation involves expressing some genes but not others

• stem cells can be used to repair / replace tissues / heal wounds

draw a label diagram to show the ultrastructure of Escherichia coli

draw a labelled diagram to show the organelles which are found in the cytoplasm of plant cells

draw a labelled diagram showing the ultra-structure of a liver cell

state one function of each of the following organelles: lysosome, Golgi apparatus, rough endoplasmic reticulum, nucleus, mitochondrion

• lysosome: hydrolysis / digestion / break down of materials

• Golgi apparatus: synthesis /sorting / transporting / secretion of cell products

• rough endoplasmic reticulum: site of synthesis of proteins (to be secreted) / intracellular transport of polypeptides to Golgi apparatus

• nucleus: controls cells activities / mitosis / replication of DNA / transcription of DNA (to RNA) / directs protein synthesis

• mitochondrion: (aerobic) respiration / generates ATP

distinguish between the structure of plant and animal cells

plant cells

• have cell walls, animal cells do not

• have plastids / chloroplasts, animal cells do not

• store starch

• fixed / more regular shape

animal cells

• have centrioles, plant cells do not

• have cholesterol in the cell membrane, plant cells do not

• store glycogen

• more rounded

using a table, compare the structures of prokaryotic and eukaryotic cells

draw a diagram to show the structure of a cell membrane

explain how the structure and properties of phospholipids help to maintain the structure of cell membranes

phospholipid structure

• hydrophobic tail / head

• head made from glycerol and phosphate

• tail made from two fatty acids

• saturated / unsaturated fatty acid (in tail)

arrangement in membrane

• phospholipids form a bilayer

• heads face outside the membrane / tails face inside the membrane / hydrophobic interior / hydrophilic exterior of membrane

• phospholipids held together by hydrophobic interactions

• phospholipid layers are stabilized by interaction of hydrophilic heads and surrounding waters

• phospholipids allow for membrane fluidity / flexibility

explain the role of vesicles in transportation of materials within cells

• vesicles are membrane bound packages / droplets

• formed by pinching off / budding off a piece from a membrane

• can carry proteins

• transported to Golgi apparatus for processing

• targeted to / transported to specific cellular organelles

• fuse with the membrane of organelle so contents of your vesicle

  • join the organelle

• transported to the plasma membrane

• fuses with plasma membrane

• fuses with platana plasma membrane releases / secret contents

distinguish between active and passive movements of materials across plasma membraned, using name exampled

• passive: oxygen across alveoli

  active transport: glucose absorption in ileum

• passive: does not require energy

  active transport: requires energy / ATP

• passive: down concentration gradient

  active transport: against concentration gradient

• passive: no pumps needed

  active transport: requires protein pumps

outline, with an example, the process of exocytosis

• vesicles carry material to plasma membrane

• vehicle fuses with membrane

• (by joining of) phospholipid bilayers

• aided by the fluidity of the membrane

• material released / expelled from the cell

• membrane flattens

outline for processes that occur in a cell during interphase, including those needed to prepare for mitosis

• DNA replication

• DNA transcription

• enzyme / protein synthesis

• cell respiration

• growth

• organelles replicated

outline the role of condensation and hydrolysis in the relationship between amino acids and dipeptides

• condensation / dehydration synthesis: water produced (when two amino acids joined)

• hydrolysis: water needed to break bond

• dipeptide → amino acids - hydrolysis

• amino acids → dipeptide - condensation occurs

draw a molecule of a-d-glucose and B-d-glucose

draw an amino acid

draw a fatty acid

draw a molecule of ribose

outline the thermal, cohesive and solvent properties of water

• water has a high specific heat capacity

• a large amount of heat cause a small increase in temperature

• water has a high latent heat of vaporisation

• a large amount of heat energy is needed to vaporise / evaporate water

• hydrogen bonds between water molecules make them cohesive / stick together

• water → high surface tension / explains how water rises up xylem

• water molecules are polar

• this makes water a good water solvent

describe the significance of water to living organisms

• surface tension → allows some organisms (insects) to move on water’s surface

• polarity / capillarity / adhesion - helps plants transport water

• ice floats - lakes / oceans do no not freeze, allowing life under the ice

• buoyancy- supports organisms

• structure - turgor in plant cells / hydrostatic pressure

• habitat - place for aquatic organisms to live

describe the use of carbohydrates and lipids for energy storage in animals

carbohydrates

• stored as glycogen in liver

• short-term energy storage

• more soluble in water for easier transport

lipids

• stored as fat in animals

• long-term energy storage

• lipids are insoluble in water so less osmotic effect

list three functions of lipids

• heat insulation

• protection of internal organs

• water proofing / cuticle

• structural component of cell membranes

functions of the male parts of the reproductive system

penis: penetrates the vagina to deposit semen close to the cervix

urethra: transfers semen during ejaculation and passage of urine during urination

seminal vesicle: produces a sugar-rich fluid that provides sperm with a source of energy to help them move

sperm duct: transfers sperm during ejaculation

epididymis: stores sperm until ejaculation

testis: sperm and testosterone production