Applications of Statistics in Biology — DU B. Sc. (Hons) Microbiology Previous Year Question Papers

(iv) What conclusion would be drawn from the findings? Biology (DSE) 1. (a) Fill in the blanks (any six) : (1x6-6) (i) Test used to compare two variances is called (ii) The difference between highest and lowest values is called (iii) Normal distribution is also called (iv) Standard normal distribution has mean S `* and variance (v) Probability of an event lies between (vi) Large sample test is based on distribution. (vii) The.probability of rejecting a true hypothesis is called age group, same gender, similar sugar level, etc. and out of these patients 10 were kept randomly under new treatment and the rest under old treatment. After three months, they measured the HbAlc of the patients and obtained HbAlc levels which are given as follows : HbAlc Level If the HbAlc levels for both groups of patients follow normal distribution with equal variances, then (i) Formulate the null and alternative hypotheses for this situation. (ii) Whether the Z-test or t-test is appropriate for testing the belief and why? (iii) Conduct a hypothesis test to see whether the new treatment is more effective than the old treatment at the 10/o significance level. (b) A researcher is testing the effectiveness of a new disinfectant against Escfeerz.c%z.cz coJz.. They apply varying concentrations of the disinfectant (in % solution) to standardized agar plates and count the number of surviving bacterial colonies after 24 Disinfectant Concentration (%) 0() Bacterial Count (CFU in hundreds) (Y) (i) Find the regression equation of Y on X. (ii) Find Y for X = 1.5%, 3.5%, 6.0%. 6. A medicine research team invented a new treatment for sugar patients and believes that it controls high sugar levels more effectively than the old one. To test their belief, they conducted a study and selected 18 sugar patients of similar conditions, that is, same (b) Find the Karl Pearson's coefficient of correlation (r) between X and Y from the following data (Nutrient concentration vs microbial enzyme activity) Y (Enayme units) 10 12 lL 15 14 2. (a) Briefly explain the following (any four)- (iii) Level of significance (iv) Central limit theorem (v) Tabulation of data (b) The bacterial c.olony count from different plates is 32, 60,40, 58 and 42. Calculate the variance and standard deviation. (6) 3. (a) State true or false (any six) : (1x6-6) (i) Regression analysis predicts one variable from another. (T/F) (ii) Scatter diagra`m shows relationship between variables. (T/F) (iii) Probability can be greater than 1. (T/F) (iv) Poisson distribution is discontinuous. (T/F) (v) Normal distribution is symmetric. (T/F) (vi) If p-value < Ci, reject null hypothesis. (Tff) (vii) F-test compares means. (T/F) (b) If, n = 10, x = 5, Z:x2 = 340, find the coefficient of variation. (6) 4. (a) Differentiate between the following (any two)- (i) Poisson vs Normal Distribution. (ii) Type I Error and Type 11 Error. (iii) Regression and Correlation.