Engineering Life: Miracles in Biotechnology (Advanced)

CBSE Science. Optional Advanced level: traditional and modern biotechnology, making insulin, Bt crops, bio-enzymes, fermenters, doubling and the microbial growth curve. Every sheet has 20 questions in three sections and an answer key, and the numbers change every time.

Open a printable sample sheet Cheat sheet: formulas and key points

Sample questions

Real questions from this chapter, as the app sets them. Tap Answer to see the answer and working.

Section A · multiple choice

1.
A bacterium doubles in number every 20 minutes. Starting with 90 cells, how many are there after 140 minutes (if none die)?
1. 23,040
2. 1,260
3. 5,760
4. 11,520
Answer
(d) 11,520
140 ÷ 20 = 7 doublings: 90 × 2⁷
2.
A fermenter's microbe count: 0 h: 40, 2 h: 45, 4 h: 49, 6 h: 71, 8 h: 107, 10 h: 104, 12 h: 103, 14 h: 90. During which interval do the microbes grow most rapidly?
1. 6 to 8 hours
2. 8 to 10 hours
3. 4 to 6 hours
4. 0 to 2 hours
Answer
(a) 6 to 8 hours
the largest rise is 36 (log phase), from 71 to 107
3.
Which of these is an example of modern biotechnology?
1. making cheese
2. fermenting dhokla batter
3. making buttermilk
4. growing Bt corn
Answer
(d) growing Bt corn
it involves moving or changing genes

Section B · short answer

4.
A culture starts with 280 bacteria, which double every 20 minutes. How many are there after 120 minutes?
Answer
17,920
120 ÷ 20 = 6 doublings; 280 × 2⁶
5.
Bacteria doubling every 30 minutes grow from 160 to 163,840. How long did this take?
Answer
300 minutes
163,840 ÷ 160 = 1,024 = 2¹⁰: 10 doublings × 30

Section C · long answer

6.
A student records the number of microorganisms in a fermenter: 0 h: 30, 2 h: 31, 4 h: 32, 6 h: 51, 8 h: 116, 10 h: 116, 12 h: 115, 14 h: 99. (a) What is the greatest rise in any 2-hour interval? (b) Name the phase between 8 and 10 hours. (c) What is the largest population recorded? (d) Suggest why the population falls at the end.
Answer
(a) 65; (b) stationary phase; (c) 116; (d) nutrients run out and toxic wastes build up, so more cells die than are formed
(a) the rises are 1, 1, 19, 65, 0, −1, −16; (b) nearly flat; (c) the highest count

Fresh sheets for your child

In the app, every Engineering Life: Miracles in Biotechnology (Advanced) sheet is new: the app remembers the questions your child has already had and leaves them out. Print the sheet as a PDF, or use notebook mode and write the answers in a notebook.

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