Read the passage given below : 1. Every morning Ravi gives his brain an extra boost. We’re not talking about drinking strong cups of coffee or playing one of those mind-training video games advertised all over Facebook. ‘‘I jump onto my stationary bike and cycle for 45 minutes to work,’’ says Ravi. ‘‘When I get to my desk, my brain is at peak activity for a few hours.’’ After his mental focus comes to a halt later in the day, he starts it with another short spell of cycling to be able to run errands.2. Ride, work, ride, repeat. It’s a scientifically proven system that describes some unexpected benefits of cycling. In a recent study in the Journal of Clinical and Diagnostic Research, scientists found that people scored higher on tests of memory, reasoning, and planning after 30 minutes of spinning on a stationary bike than they did before they rode the bike. They also completed the tests faster after pedalling.Exercise is like fertilizer for your brain. All those hours spent on exercising your muscles, create rich capillary beds not only in leg and hip muscles, but also in your brain. More blood vessels in your brain and muscles mean more oxygen and nutrients to help them work. When you pedal, you also force more nerve cells to fire. The result : you double or triple the production of these cells — literally building your brain. You also release neurotransmitters (the messengers between your brain cells) so all those cells, new and old, can communicate with each other for better, faster functioning. That’s a pretty profound benefit to cyclists.4. This kind of growth is especially important with each passing birthday, because as we age, our brains shrink and those connections weaken. Exercise restores and protects the brain cells. Neuroscientists say, ‘‘Adults who exercise display sharper memory skills, higher concentration levels, more fluid thinking, and greater problemsolving ability than those who are sedentary.’’5. Cycling also elevates your mood, relieves anxiety, increases stress resistance, and even banishes the blues. ‘‘Exercise works in the same way as psychotherapy and antidepressants in the treatment of depression, maybe better,’’ says Dr. Manjari. A recent study analyzing 26 years of research finds that even some exercise — as little as 20 to 30 minutes a day — can prevent depression over the long term.Answer the following questions briefly : (i) How does exercise help the brain ?  (ii) Why does Ravi do a circuit of ‘ride, work, ride’ ?(iii) What is the work of neurotransmitters ?(iv) What benefits other than greater brain activity does one get from cycling ?(v) Why is exercise so important for adults ?(vii) How is exercise itself a stress ?