1)Give two reasons which explain why plants lack excretory organs like those in animals

Question

2)In nature most plants are cross pollinated rather than self pollinated;
a)List 3 features that hinder self pollination in most plants
b)State one advantage of cross pollination
3)Name one protein and one vitamin which is important in the normal blood clotting
4)In each case,outline the function of the following structures of a leaf;
a)Cuticle
b)Guard cells
c)Palisade cells
5)State three properties of monosaccharides
6)List two features of small intestine that increase in surface area
7)A student viewed and drew a plant cell of diameter 4mm using a light microscope with an eyepiece lens marked ×1 and an objective lens marked ×5.How many cells were linearly arranged along the microscope field of views whose diametre was 8 mm
8)State three functions of blood other than transport

Answer 1

Here are the answers to your questions:

1. Reasons why plants lack excretory organs:

   • Photosynthetic Process: Plants are capable of photosynthesis, which allows them to utilize carbon dioxide from the atmosphere and release oxygen as a byproduct, thus effectively managing gas exchange without the need for specialized excretory structures.
   • Storage of Waste Products: Plants can store waste products like tannins and resins in vacuoles or in particular tissues, which minimizes potential harm and reduces the necessity for excretion like in animals.

2. a) Features that hinder self-pollination:

   • Dioecy: Many plants have male and female flowers on different individuals, which requires cross-pollination.
   • Temporal Dichogamy: Some flowers mature their stamens and pistils at different times, preventing self-pollination.
   • Structural Barriers: Certain flowers have physical structures that prevent pollen from fertilizing the same flower’s ovules.

   b) Advantage of cross-pollination:

   • Increased Genetic Variation: Cross-pollination promotes genetic diversity, which can enhance adaptability and resilience to environmental changes and diseases.

3. One protein and one vitamin important in blood clotting:

   • Protein: Fibrinogen
   • Vitamin: Vitamin K

4. Functions of structures in a leaf:

   • a) Cuticle: The cuticle is a waxy layer that helps reduce water loss by evaporation and protects the leaf from pathogens.
   • b) Guard Cells: Guard cells regulate gas exchange by opening and closing the stomata, allowing for the intake of carbon dioxide and the release of oxygen while minimizing water loss.
   • c) Palisade Cells: Palisade cells are densely packed with chloroplasts, and their primary function is to carry out photosynthesis efficiently by capturing sunlight.

5. Three properties of monosaccharides:

   • Solubility: Monosaccharides are generally soluble in water due to their hydroxyl (-OH) groups.
   • Sweetness: Many monosaccharides, such as glucose and fructose, have a sweet taste.
   • Reactivity: They can easily participate in chemical reactions, such as forming glycosidic bonds or isomerizing.

6. Two features of the small intestine that increase surface area:

   • Villi: The small intestine is lined with finger-like projections called villi, which increase the surface area for absorption.
   • Microvilli: Each epithelial cell on the villi has tiny hair-like structures called microvilli, further amplifying the surface area available for nutrient absorption.

7. Calculation of cells linearly arranged:

   • Diameter of the field of view = 8 mm
   • Diameter of one plant cell = 4 mm
   • Number of cells linearly arranged = Diameter of field of view / Diameter of one cell = 8 mm / 4 mm = 2 cells

8. Three functions of blood other than transport:

   • Regulation of Body Temperature: Blood helps to regulate body temperature through the distribution of heat.
   • pH Regulation: Blood maintains the body’s pH balance by buffering acids and bases.
   • Immune Response: Blood contains white blood cells and antibodies that play a crucial role in immune defense against infections.