151. Regulation of gene expression is important because it:
Answer: B. allows the cell to express proteins when needed and is the basis of differentiation
Biology Class 11 Unit 13: Chromosome and DNA MCQs
228 multiple choice questions with the correct answer for each. Tap an option to check yourself, or switch on "Show all answers". This is page 4 of 5.
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152. The mature human body has about how many different cell types?
Answer: C. 200
153. Different cell types differ because of:
Answer: B. differential gene expression
154. In negative control, gene expression is:
Answer: B. turned off by a repressor protein
155. In positive control, gene expression is:
Answer: B. turned on by an activator protein
156. A repressor binds to the:
Answer: B. operator region
157. The lac operon is a classic example of gene regulation in:
Answer: B. bacteria
158. The lac operon consists of a regulatory gene and how many structural genes?
Answer: B. Three (z, y and a)
159. The i gene produces the:
Answer: C. repressor protein
160. The z gene codes for:
Answer: C. beta-galactosidase
161. Beta-galactosidase hydrolyses:
Answer: B. lactose
162. When lactose is absent, the repressor:
Answer: B. binds the operator and prevents transcription of structural genes
163. When lactose is present, the repressor:
Answer: B. is inactivated by the inducer (lactose), so transcription occurs
164. The inducer of the lac operon is:
Answer: B. lactose (allolactose)
165. A mutation is a change in:
Answer: B. the DNA sequence or chromosome structure or number
166. Agents which cause mutations are called:
Answer: B. mutagens
167. The organism in which a mutation occurs is called a:
Answer: B. mutant
168. A physical mutagen is:
Answer: C. UV rays, X-rays and gamma rays
169. A chemical mutagen is:
Answer: C. colchicine, mustard gas and nitrous acid
170. Mutations which occur naturally are called:
Answer: B. spontaneous (natural) mutations
171. Mutations produced artificially are:
Answer: B. induced mutations
172. A change in a single or a few nucleotides is a:
Answer: B. point (gene) mutation
173. A change in the structure or number of chromosomes is:
Answer: B. a chromosomal mutation (aberration)
174. Replacement of one base by another is:
Answer: C. base substitution
175. Addition or removal of one or more nucleotides causes a:
Answer: B. frameshift mutation
176. A frameshift mutation results in:
Answer: B. a completely new codon sequence and a non-functional protein
177. Most mutations are:
Answer: C. harmful
178. Mutations are considered the driving force of:
Answer: B. evolution
179. Harmful mutations are removed from the gene pool by:
Answer: B. natural selection
180. Examples of harmful mutations include:
Answer: B. cancer, microcephaly, Down syndrome and sickle cell anaemia
181. Down syndrome is characterized by:
Answer: B. 2n plus 1 with trisomy 21
182. The total chromosome number in a Down syndrome child is:
Answer: C. 47
183. Down syndrome results from:
Answer: B. non-disjunction of chromosome 21 during maternal meiosis
184. A symptom of Down syndrome is:
Answer: B. a single crease in the palm and a flattened nose
185. Klinefelter's syndrome has the chromosome constitution:
Answer: B. 44 + XXY
186. Klinefelter's patients are:
Answer: B. males with some feminine characters and small testes
187. Klinefelter's syndrome can be treated with:
Answer: B. testosterone at puberty, but it does not help infertility
188. Turner syndrome has the chromosome constitution:
Answer: B. 44 + XO (45 chromosomes)
189. Turner syndrome patients are:
Answer: B. females with short height, webbed neck and infertility
190. Growth hormone and estrogen therapy are used for:
Answer: C. Turner's syndrome
191. Sickle cell anaemia is due to replacement of glutamic acid by:
Answer: B. valine at position 6 of the beta chain
192. Sickle cell anaemia is caused by:
Answer: B. a recessive gene, inherited from both parents
193. Treatment of sickle cell anaemia includes:
Answer: B. blood transfusions, pain relief, fluids, and bone marrow or stem cell transplant
194. Phenylketonuria (PKU) is the inability to break down:
Answer: C. phenylalanine
195. In PKU the defective enzyme is:
Answer: B. phenylalanine hydroxylase
196. PKU is inherited as:
Answer: C. autosomal recessive
197. The treatment of PKU is a diet extremely low in:
Answer: B. phenylalanine
198. The special infant formula for PKU is:
Answer: C. Lofenalac
199. Chromosomes are made of:
Answer: C. DNA and histone proteins
200. The anticodon of a tRNA is:
Answer: B. complementary to the corresponding codon of mRNA
About Biology Class 11 Unit 13 MCQs (Federal Board)
These 228 Biology MCQs cover Class 11 Unit 13: Chromosome and DNA of the Federal Board (FBISE) HSSC-I (1st Year / Class 11) syllabus. They are SLO-based MCQs as per the new pattern for FBISE exams. Each question has four options and the correct answer is shown, so you can practise for the annual examination and find the topics you still need to revise. The questions are split over 5 pages of 50. Use the Print button to save this chapter as a PDF.