CHROMOSOMES

Chromosomes consist of one DNA molecule. Each somatic cell of your body has 23 pairs of chromosomes, one member of each pair contributed by your mother and the other by your father. (In egg and sperm cells - there are 23 individual chromosomes, not chromosome pairs.) One pair are the sex chromosomes, which can come in two forms, X and Y. A pair of X's gives a female, and an XY results in a male.

MONOCOT LEAF

The following figures show transverse sections of monocot leaves.

NOTICE HOW THE STOMATA ARE DISTRIBUTED (COMPARED TO DICOT LEAVES)?
YOU CAN ALSO SEE STOMATA ON THE UPPER SURFACE, RIGHT?
EVER WONDER WHY?
(TRY TO FIGURE OUT WHY?)

XEROPHYTE, MESOPHYTE AND HYDROPHYTE

XEROPHYTE
Plants that live in conditions where water is scare (for example in the desert)

MESOPHYTE
Land plants living in environment with moderate amount of moisture.

HYDROPHYTE
A plant adapted to grow in water.

Transverse Section of a Mesophyte Leaf

Transverse Section of a Xerophyte Leaf

Transverse Section of a Hydrophyte Leaf

Notice the adaptations of the Xerophyte and the Hydrophyte leaves?

• Xerophyte leaf needs to conserve as much water as possible so it tends to curl so as not to expose the stomata. So the stomata is hidden inside the curl inner side of the leaf. Apart from this, it has a very thick waxy cuticle and some may even have leaf hairs. Generally leaves of the xerophyte are succulent to store water as much as possible.
• Hydrophyte leaf needs to be able to float so that it can trap as much light energy from the sun as possible. To enable it to float the leaf has unusually large intercellular air spaces for storing air which in turn provides BUOYANCY. Apart from this, the stomata can be found on the upper surface (unlike the mesophyte - the stomata are found on the lower surface of the leaf).
  

ONION BULB

DO YOU KNOW THAT AN ONION BULB ACTUALLY CONSISTS OF LEAVES (SCALE LEAVES)?

DO YOU KNOW THAT AN ONION PLANT IS AN EXAMPLE OF A MONOCOT?
NOTE: BE AWARE THAT THERE MAY BE QUESTIONS IN THE PRACTICAL PAPER ASKING YOU TO MAKE A FULLY LABELLED DRAWING OF AN ONION BULB. NOTE THE LEAVES AND THE STEM TISSUE.
FOOD TEST MAY ALSO BE ASKED AND DO NOT BE SURPRISE THAT AN ONION BULB CONTAINS REDUCING SUGAR!!! (NOTE: WHEN COOKING ONION, THE DARK BROWN CARAMEL IS ACTUALLY THE SUGAR!!!)


The following figure shows how an onion bulb is to be drawn (Longitudinal Section!!!)

CHLOROPLAST

CHLOROPLAST AS CAN BE SEEN UNDER A MICROSCOPE

A FIGURE SHOWING THE INTERNAL STRUCTURE OF A CHLOROPLAST

NOTE: CHLOROPLAST - SITE WHERE PHOTOSYNTHESIS TAKES PLACE

MUSCLE CRAMP

What is cramp?

A cramp is an involuntary and forcibly contracted muscle that does not relax. If you haven't experienced it, count yourself lucky. Try clenching your thigh muscles. Then imagine squeezing them so hard it hurts and holding them like that for a minute. Cramp locks up your leg in a painful grip, you certainly can't pedal. Sometimes, you'll get a small cramp where you can soft pedal but if you're racing, the chances are it's game over as you're not going to be able to force the pace much and often this small tension is a sign that you're going to cramp up a lot.

What causes cramp?

• Dehydration
• Accumulation of Lactic Acid
• Electrolyte imbalance