BIOLOGY PRACTICAL ACTIVITIES

Examining the stages of mitosis

About 2 mm of a root tip of onion bulb is cut off and placed on a microscope slide.

A stain e.g. aceto-orcein is added and the root tip macerated using a scapel. A cover slip is added and observations made. Different stages of mitosis can be observed.

Examining the stages of meiosis

An unopened bud of Tradescantia is obtained The anther is removed and placed on a microscope slide. A few drops of hydrochloric acid and acetic-orcein stain are added.

A cover slip is placed on the anther. Pressing the cover slip gives a thin squash, which is observed under the microscope. Different stages of meiosis are observed.

To observe the structure of Rhizopus

Rhizopus grow on moist bread left under suitable temperature A piece of moist bread is placed on a petri¬-dish or enclosed in a plastic bag and observe daily for four days. Under a low power microscope the sporangia and stolons can be observed.

To examine spores on sori of ferns

Obtain the fern plant. Detach a frond from the plant and observe the under-side using a hand lens to see the raised brown patches – the sori. Open up the sorus to observe the sporangia.

Examine insect and wind pollinated flowers

Obtain insect pollinated flowers e.g. crotalaria, hibiscus/Ipomea, Solanum, incunum. Note the scent, colour and nectar guides. A description of the calyx, corolla, androecium and gynoecium is made.

Obtain a wmd pollinated flower e.g,’ maize, star-grass, sugar-cane, Kikuyu grass. Observe the glumes, spikes and spikelet. Examine a single floret, and identify the androecium and gynoecium.

Classifying fruits

Obtain different fruits – oranges, mangoes, maize, castor oil, bean pod, black jack . Observe the fruits, classify them into succulent, dry-dehiscent or indehiscent.

Dissection of Fruits

Obtain an orange and a mango fruit. Make a transverse section. Observe the cut surface and draw and label the parts. Note that the fruit is differentiated into epicarp, mesocarp and endocarp.

Obtain a pod of a legume. Open up the pod and observe the exposed surface. Draw and label the parts. Note that the fruit wall is not differentiated.

Dispersal of fruits and seeds

Obtain animal dispersal fruits, like oranges, tomatoes, black jack, sodom apple. Identify the way by which each is adapted to dispersal by animals. Obtain wind dispersed fruit/seed e.g. Nandi flame, Jacaranda Sonchus, cotton seed, Tecoma.

EVALUATION

1. How do you identify the stages of mitosis?
2. What are the 5 stages of mitosis and what is occurring at each?
3. What is a good way to remember the stages of mitosis?
4. How do you identify the stages of meiosis?
5. What are the 5 stages of meiosis?
6. What are the 4 stages of the cell cycle?
7. How can you observe the structure of Rhizopus?
8. What is the structure of Rhizopus?
9. How do you observe spore in fern leaves?
10. What is sori in ferns?
11. How will you describe spores?
12. What is the difference between insect and wind pollinated flowers?
13. What are characteristics of wind water and insect pollinated flowers?