Kassumec-Jet Biology Exam 2024

Examination Overview

• Kenya Certificate of Secondary Education examination in Biology theory.
• Duration of exam: 2 hours.
• Total score for the paper: 80 marks.

Examination Structure

• Two sections: A and B.
• All questions in Section A must be answered.
• Section B requires answering Question 6 (compulsory) and either Question 7 or 8.

Haemophilia

• Genetic disorder linked to a recessive sex-linked gene.
• A phenotypically normal couple can have a hemophiliac son.

Genotypes of Parents

• Father: X^H Y (normal, carries normal allele)
• Mother: X^H X^h (normal, carriers the hemophilia allele)

Offspring Genotypes

• Offspring possibilities: X^H Y (normal son), X^h Y (hemophiliac son), X^H X^H (normal daughter), X^H X^h (carrier daughter).

Commonality in Males

• Males have only one X chromosome, so if they inherit the hemophilia allele on the X chromosome, they will express hemophilia.

Plant Transport Mechanisms

• A study of a plant's water uptake, nutrient absorption, and sugar translocation under different environmental conditions.

Observations Under Conditions

• Normal Conditions: Water uptake - 15 mm/hr, Nutrient absorption - 8 Mg/hr, Sugar translocation - 12 Mg/hr.
• High Salinity: Water uptake drops to 10 mm/hr; nutrient absorption and sugar translocation decrease to 5 Mg/hr and 7 Mg/hr respectively.
• Drought: Further decline with water uptake at 6 mm/hr, nutrient absorption at 4 Mg/hr, and sugar translocation at 5 Mg/hr.

Comparisons

• Water uptake is significantly reduced during high salinity (from 15 to 10 mm/hr) indicating stress on the plant.
• Sugar translocation decreases from 12 Mg/hr in normal conditions to 5 Mg/hr during drought, indicating affected metabolic processes.

Plant Responses to Drought

• Physiological adaptations include closing stomata to reduce water loss and deep root systems for better water access.

Physiological Processes

• Transpiration: Process involved in water transport in plants.
• Food Test: Specific test to identify substances like starch or sugar within the plant.

Food Test Results

• Positive results indicate the presence of the tested nutrient and possible influences on plant growth.

Section B Focuses

• Germination study of cowpeas (Vigna unguiculata) showing growth measured over time, with an emphasis on dry mass accumulation.

Graphing and Data Analysis

• Graphical representation of dry mass of embryos against time to visualize growth patterns.
• Expectation of an exponential growth curve indicating rapid growth phases during germination.

Plant Hormones

• Abscisic Acid (ABA): Plays a role in stress responses, including drought tolerance.
• Florigens: Promotes flowering in response to environmental cues.

Inhalation Mechanism in Fish

• Detailed description of the physiological processes involved in respiration among bony fish species, including water flow over gills and gas exchange mechanisms.

Plant Responses to Stimuli

• Investigation of how young herbaceous plants respond to unidirectional stimuli like light (phototropism) and gravity (gravitropism), detailing significance for survival and growth.

Prepare for the Kenya Certificate of Secondary Education with this Biology theory paper. This quiz will test your knowledge and understanding of biological concepts as outlined in the syllabus. Make sure to answer the questions within the specified time to simulate exam conditions.