• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Factors afftecting growth of pollen grains

Extracts from this document...

Introduction

TITLE: FACTORS AFFECTING GROWTH OF POLLEN GRAINS OBJECTIVE: To investigate the effects of different concentrations of sucrose solutions and different concentration of boric acid in the growth of pollen grains. INTRODUCTION: Pollen grains are produced in the pollen sacs of the anther. Each microspore mother cell undergoes meiosis to produce four haploid cells, each of which produces a pollen grain or a microspore. The haploid nucleus of a pollen grain divides by mitosis to produce two haploid cells which function as male gametes. The pollen grain secretes a thin inner wall, the intine, and a thick outer wall, the exine. The mature pollen grains, containing the male nuclei, are released when the anther wall dries out and the anther splits. On landing the stigma, the pollen grain absorbs water. The growth of pollen tube is stimulated by the secretion of sucrose by epidermal cells of the stigma. There are also a number of other factors affecting growth of pollen tubes which includes temperature, pH, and concentration of calcium, boron, and metal ions such as copper and potassium ions. The pollen tube continues to grow down the style as it is attracted by chemicals produced by micropyle of the ovule. ...read more.

Middle

0.3M sucrose + boric acid 0.5M sucrose + boric acid 1.0M sucrose + boric acid 30 9 x 9.9�m = 89.1�m 10 x 9.9�m = 99.0�m 10 x 9.9�m = 99.0�m 60 10 x 9.9m = 99.0�m 11 x 9.9m = 108.9�m 15 x 9.9m = 148.5�m 100 division graticule = 99 division stage 1 division graticule = 0.99 division 1mm = 100 division stage micrometer (�m) 1 small division = 0.01mm DISCUSSION: 1. Lillium anthers were chosen in this experiment because they have nice meiotic figures as they produce the male gametophyte, that is, the chromosomes are more easily observed than in many other species. 2. To investigate the factors which affect pollen tube growth, the concentration of sucrose factor for an example, pollen grains are placed in a sucrose solution and the pollen tubes which germinates is then observed and measured. The length of pollen tube indicates how well the factor affects pollen tube growth. 3. In this experiment, the anther was first gently tapped to remove small pollen grains that are barely visible to the human eye into the beaker containing the different concentrations of sucrose and boric acid. 4. By using the different concentrations of sucrose, we can determine the effect of sucrose on germination of pollen grains. ...read more.

Conclusion

8. During the experiment, some pollen grains had two pollen tubes emerging from it in different directions. This happens as the pollen tube has no specific direction (usually they are attracted the chemicals produced by the micopyle of the ovule). The truth is that pollen tubes can germinate from 1, 2 or 3 poruses of the pollen grain, divide and branch during their growth in the ovary. The branches are of different length and give secondary splits. Special short branches are formed near the micropyle of the ovule. They grow into top part of integuments. The pollen tubes start to branch profusely near the placental surface. In that place they are likely to react to the stimulus from mature ovules which seem to be dispersed in the exudate covering placenta. 9. The hanging drop technique is used in this experiment as it is a well-established method for examining living, unstained, very small organisms. The traditional procedure employs a glass slide with a circular concavity in the centre into which a drop of fluid, containing the pollen grains, hangs from a coverslip. This simple preparation allows students to observe extremely small sized pollen grains in sucrose solution under the microscope effectively and easily. CONCLUSION: As concentration of sucrose increases, the number of pollen grains which have germinated (pollen tube) also increases. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Exchange, Transport & Reproduction section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Exchange, Transport & Reproduction essays

  1. Marked by a teacher

    Biology coursework planning - the effect of lead chloride on the growth of cress ...

    5 star(s)

    mediums Medium in which cress seeds are grown Average length of shoot of cress seeds (mm) Cotton pad 46.7 Filter paper 36.0 Cotton wool 39.9 Note: All figures in the table are correct to 3 significant figures as per the Institute of Biology guidelines.

  2. Marked by a teacher

    Reproduction, Gamete formation and fertilisation

    4 star(s)

    * Once one sperm makes contact with the zona pellucida of the egg cell the acrosome reaction occurs- this is where digestive enzymes released from the acrosome of the sperm. * These enzymes digest the zona pellucida, so that the sperm can move through it to the plasma membrane of the egg cell.

  1. To find out the factors affecting the refractive index of liquid by using different ...

    Even if I raised the temperature, the molecule moved faster but they are still moving around randomly. The speed of light only change very little with increasing temperature. The design of the experiment should be more precise in order to detect that little change.

  2. Biology: Field Project

    The food that the plant produces is essential for its growth so the affect that light intensity has upon photosynthesis will have an adverse affect on the growth of Betulaceae. The light is involved in the photosynthesis equation; the natural source of the light is the sunlight: Carbon Dioxide +

  1. Meiosis in Pollen Mother Cells

    The watch was held with forceps or a test tube holder and was warmed gently over a low Bunsen flame until the liquid just begins to steam. 4. It was left for 10minutes to take up the stain, then the anthers were placed on a microscope slide.

  2. the role of the microbiology department

    When many examinations have to be made, even skilled and conscientious workers may from time to time make mistakes. Staff should be encouraged to recognise and report any likelihood of their having made a mistake, and should not be made afraid to confess the possibility.

  1. Statistical Technique.

    Sucrose and lactose are carbohydrates classed as disaccharides, they contain two sugar units. They are made when two monosaccharides join together by a reaction when one molecule of water is removed. This is known as a condensation reaction and produces a bond between the two molecules called a glycosidic link.

  2. This experiment aims to investigate the effects of 4 different types of fish food ...

    Salmon do not convert all their food into body mass or energy (known as the Food Conversion Ratio or FCR) thus some of the food they ingest is wasted. In fact, salmon fry have a FCR of 0.9 to 1.0 whereas adult salmon have a FCR of 1.2 to 1.3 (2).

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work