Explain how minerals move into plants.

Outline the conditions needed for the germination of a typical seed.

Following germination of seeds, plants undergo a rapid increase in the number of cells. Describe stages in the cell cycle that result in this increase of cells.

Remember, up to TWO “quality of construction” marks per essay.

a. minerals bound to soil particles;
b. examples of three nutrients from: phosphate, nitrate, magnesium, iron, calcium, potassium, sodium, magnesium;
c. minerals dissolve in water;
d. mass flow causes movement of minerals with movement of water through soil;
e. minerals diffuse down a concentration gradient towards roots (as the mineral concentration next to the roots is continuously decreasing);
f. minerals enter the plant through roots;
g. by active transport / use of ATP;
h. branching of roots increases surface area for absorption of minerals;
i. root hairs increase surface area (for the absorption of minerals);
j. hypha of (mutualistic) fungi may enhance movement of selected ions into roots / increase surface area;
k. root hairs have many mitochondria to provide energy/ATP for active transport;
l. export of H+ creates electrochemical gradient / displaces ions bound to soil/clay;
m. that causes positive mineral ions to diffuse into (root) cells;
n. negative mineral ions cross membrane linked to H+ ions moving down (H+) gradient;

Remember, up to TWO “quality of construction” marks per essay.

a. water to rehydrate the seed / activate metabolic processes;
b. oxygen for aerobic respiration as seed germinates;
c. suitable temperature for enzyme activity;
d. each type of seed has specific temperature requirements / temperature requirements ensure that seeds germinate at the correct time of year;
Do not accept a simple list of factors without details.

Remember, up to TWO “quality of construction” marks per essay.

a. growth phase/G-1: synthesis of proteins/cytoplasm/organelles;
b. synthesis phase/S-phase: replication of DNA;
c. second growth phase/G-2: continued growth of cytoplasm/molecular synthesis/duplication of organelles;
d. prophase: chromosomes super-coil to prepare for mitosis / nuclear envelope disappears / spindle fibres form;
e. metaphase: chromosomes line up at equatorial/metaphase plate / spindle fibres attach to centromeres/chromosomes;
f. anaphase: chromatids move along microtubules/spindle fibres move chromatids toward opposite poles;
g. telophase: nuclear membranes form around each cluster of chromosomes;
h. cytokinesis: new plasma membrane forms between the nuclei / cell plate forms;
i. a new cell wall forms;
j. (mitosis) results in two cells with identical nuclei;

Names of phases are required to earn the mark.
Award marks for a clearly drawn correctly annotated diagram.

Students tended to perform well on this question though it was rare for students to demonstrate detailed knowledge of the mechanism of active transport in terms of ion exchange.

Students found it easier to list the conditions required for germination rather than outlining the conditions required.

Many students earned marks by outlining the stages of mitosis though a number were not clear on when spindle fibres form and when they attach, commonly indicating that this occurs in metaphase. Some students muddled the mechanisms of meiosis and mitosis. The distinctions between cytokinesis in plant and animal cells does not seem to be well understood. The events that occur in the different stages of interphase appears to be less well known.