Cell (i) A-nucleolus B – endoplasmic reticulum C – mitochondria (ii) digestive enzymes (iii) II (released via pancreatic duct) Pancreatic acinar cell is an exocrine

cell, its secretion is transported by duct

Nucleolus & ribosomes Nucleolus is a conspicuous

rounded structure inside the nucleus. There may be one or

more in number, its function is to make ribosomes by combining rRNA with proteins.

RER & Golgi apparatusFunctional relationship RER is a complex system of flattened membrane bound

sacs running throughout the cytoplasm. It has ribosomes on its surface..

Golgi apparatus consists of a stack of flattened membrane bound sacs and a system of associated vesicles. D is formed by the fusion of the vesicles which are pinched off from E.

Structural relationship: E is concerned with synthesis and tranpsort of

proteins. Protein synthesized at E will be transported, further processed and packaged in Golgi apparatus.

Functions of lysosomes / Golgi vesicles- secretion of enzymes e.g. hydrolytic enzymes / digestive

enzymes- secretion of hormones e.g. insulin / glucagon / thyroxine

,

Diagram showing the structural and functional relationship between nucleus, ribosomes, ER and Golgi apparatus.

Trilaminar structure of cell membrane?? 2003 AL

Water potential

A – pressure potentialB – water potentialC – osmotic potential Water potential of a cell is defined as the difference in

chemical potential between water inside the cell and pure water at the same temperature and pressure.

  Pressure potential is defined as the component of the cell’s

water potential that is due to hydrostatic pressure.

  Osmotic potential is defined as the component of the cell’s

water potential that is due to the presence of solutes.

  water potential = pressure potential + osmotic potential

3 (a) (i) water potential of cell A =? water potential of cell B =?

Water potential of cell A =, <, > water potential of cell B water flow from cell _ to _ (ii) (1) water potential of the cells at equilibrium is equal to the water potential of surrounding solution.   (2) cell A at equilibrium pressure potential = water potential - osmotic potential

3(b) leaf cells of plant!! Chemicals dissolve in soil solution lower w.p.of

soil water decrease w.p. gradient between root hair cells and soil solution water uptake of root by osmosis reduced.

Reduced water supply to leaf cells cannot compensate for the loss due to transpiration.

Leaf cells lose water due to reduced w.p. become flaccid / lose turgidity leaf cannot supported by turgidity of cells

wilt

3 (c)Organic solvent e.g. acetone /

chloroform / alcohol dissolve the lipid components of cell membranes of beetroot cells red pigments diffuse out whether the solution turn red or remain colourless depend on their

solubility in these solutone.g. acetone will turns red VS chloroform?

Paraffin oil Not affect the cell membrane of

beetroot cell remain colourlessEffect of temperature on membrane

permeability of beet root cell Temp kinetic energy of red pigments ?? Kinetic energy of protein & lipid components of cell membraneHigh temp denaturation of protein component of cell

membrane

4. Plants and animals adapted to desiccation (97 AL)

Desiccation (water) /High salt content (water + salt)Desert (water + hot)

1. Body covering by impervious to water

Cornified epithelium of skin of mammal Scales of reptiles Wax cuticle / exoskeleton of insects Shells of gastropods Waxy cuticle covers epidermis of leaf /

shoot Bark has suberin in plants

2. Respiratory surfaces are protected from desiccating effect of air

Mammal – lung sunken deep Insect – trachea inside body spiracles covered by

valves Plants – parenchyma under

epidermis stomata

3. Reproductive mechanism – protect gametes and embryos

Mammal – internal fertilization, viviparity Gymnosperm and angiosperms – male gamete in pollen tube,

seeds?? Mosses and ferns – spores, male

gametes only released in water

4. Acquisition of water

Mammal – drink water Plants – rhizoids, lateral roots /

deep main roots, root hair

5. Maintain the water balance / water storage

Mammals – kidney tubule hypertonic

urine - loop of Henle - colon absorbs water Birds – uric acid Plants – succulents / hairy epidermis /

needle shaped leaves

6. Behaviour

Earthworms – burrows Animals seek shadeNocturnal activity Migration

Photo studye.g. 98I Q 2 – xerophyte 1. Thick cuticle 2. Multiple epidermis3. Sunken stomata and hairs in

epidermal invagination Be careful – Cactus / mangrove

(halophyte) / camel