1. Put an onion
in moist absorbent paper in a warm place to obtain roots. Cut off 1 cm
lengths
from the ends of roots and fix them in a solution of 1 part glacial
acetic acid
to 3 parts 95% alcohol. Leave for 24 hours. Put a piece of root in a
drop of aceto-carmine
on a slide. Cut off 3 mm of the tip and discard the rest. Gently warm
over a
spirit lamp. Place a coverslip over the drop of stain. Wrap absorbent
paper
over the thumb, then gently squash the pieces of root tip by pressing
on the
coverslip with a rolling motion. Be careful! Do not break the coverslip
because the broken pieces are very sharp and dangerous. Do not
allow the coverslip to slide.
These
cells will show stages in mitosis.
2. In the morning, cut 5 mm from the end of a growing root of onion or
pea. Cut
the piece of root twice longitudinally. Put the longitudinal sections
in a drop
of carmine acetic acid on a microscope slide. Cover with a coverslip
and heat
to boiling point holding the slide with forceps and holding it over a
small
Bunsen burner flame by moving the slide backwards and forwards to
prevent excessive heating in one place. Put a drop of 2% acetic acid at
the
side of the coverslip and draw it across under the coverslip with
absorbent
paper on the opposite side. Press down on the coverslip with a scalpel
handle
to squash the cells. Be careful not to break the coverslip as the
broken pieces are
very sharp. Examine the cells under high power. Look for dividing
nuclei at
different stages of development, prophase, metaphase, anaphase and
telophase.
Count the number of chromosomes, e.g. onion 16 and pea 14. Find the
different
stages and count the number of separate stages. Use this information to
estimate the relative lengths of time for each stage during mitosis.
The
process takes about two hours with prophase taking two-thirds of the
time.
Repeat the experiment with root tip specimens taken at different times.
3. Plant an onion or shallot in moist absorbent paper in a warm place
to obtain
roots. Cut off 1 cm lengths from the ends of roots and fix them in a
solution
of 1 part glacial acetic acid to 3 parts 95% alcohol. Leave for 24
hours. Put a
piece of root in a drop of aceto-carmine on a slide. Cut off 3 mm of
the tip
and discard the rest. Gently warm over a lamp (light) bulb. Place a
coverslip
over the drop of stain and apply gentle pressure to separate the cells.
These
cells will show stages in mitosis.
| Hermaphrodite flowers | Stamens and pistil in the same flower, Most familiar flowers, legumes, rose, potato, Grevillea, Primula |
| Monoecious (unisexual) (diclinous) | Stamens and pistil in separate flowers on the same plant, beech, oaks, hazel, sycamore |
| Dioecious (unisexual) | Stamens and pistil in separate flowers on different plants, date palm, willow, poplar, hop |
| Ovule | Seed |
| Integuments | Seed coats |
| Nucellus | Shrivels to thin papery layer |
| Fusion nucleus of the embryo sac | Endosperm tissue for food storage and nutrition of the embryo |
| Ovum | Embryonic plant |
| Antipodals | Usually shrivel, sometimes persists as absorbing mechanism for endosperm |
| Synergids | Usually shrivel and are absorbed by the developing embryo |
| Fruit type | Name | Description | Examples |
| Dry indehiscent fruits | Achene | 1 carpel, one seed attached to hard pericarp | Compositae family, buttercup, Clematis (strawberry, rose), cashew, sunflower |
| " | Caryopsis or grain | usually 1 carpel, ovary wall, pericarp and seed coat, testa, fused together | cereals, grasses, wheat, maize, rice |
| " | Samara | pericarp forms wings | maple, sycamore, ash |
| " | Cypsela | 2 carpels, like achene but inferior ovary | Compositae family, dandelion, sunflower, daisy |
| " | Schizocarp | syncarpous ovary splits when ripe | geranium, mallow, hollyhock |
| " | Nut | more than 1 carpel, woody wall | macadamia nut, hazel nut |
| Dry dehiscent fruits | Follicle | 1 carpel, dehisce along one margin | oleander Nerium, Delphinium, Grevillea, kurrajong, larkspur, columbine |
| " | Legume, pod | 1 carpel, dehisce along both margins | Family Leguminosae, pea, bean, lentil, Acacia, peanut (ground nut), cowpea, tamarind, Corydalis, Cleome |
| " | Lomentum | 1 carpel, legume pod constricted between seeds | clover, Cassia, bird's foot trefoil |
| " | Siliqua (silicule) | 1 carpel, legume with constrictions between seeds | pod of Family Cruciferae, shepherd's purse, stock, cabbage |
| " | Capsule | 3+ carpels, dehisce by pores or splits | Eucalyptus, Leptospermum, poppy, lily pansy, violet, iris, snapdragon, scarlet pimpernel, cotton, castor oil, kapok, okra, roselle, opium |
| True succulent fruits, fleshy fruits | Berry | 2+ carpels, pericarp = skin epicarp, fleshy or fibrous
mesocarp, thin
skin endocarp (pepo or gourd has one cavity, pulp interior) |
chillies, tomato, capsicum, egg plant, banana, gooseberry, date, currant, grape, avocado, papaya, passion fruit, allspice pimento, pomegranate, guava, mangosteen, carambola (star fruit) (pepo: pumpkin, melon, cucumber, marrow, squash, snake gourd) |
| " | Drupe | 1 superior carpel, pericarp = skin epicarp, fleshy or fibrous mesocarp, thin skin endocarp stony endocarp encloses seed (kernel) | "stone fruit", cherry, peach, apricot, plum, almond, cocoa, coconut, mango, cashew, coffee (walnut 2 carpels), pepper, nutmeg |
| False succulent fruits | Pome | "core" = ovary, fleshy receptacle | apple, pear, quince |
| " | Hesperidum | many fused carpels, with pulp and tough rind containing oil glands | Citrus, orange, grapefruit, lemon, lime |
| " | Aggregate fruit, syncarp | collection of several carpels from one flower | pineapple, custard apple, rose hip (achenes), strawberry (achenes), blackberry, breadfruit, jack fruit, fig (called syconium) raspberry, blackberry, mulberry, pandanas |