A
(2022· 山东夏津一中模拟)Exercise and a healthy diet in childhood leads to adults with bigger brains and lower levels of anxiety, according to a new research in mice.
Though diet and exercise are consistently recommended as ways to promote health, this study is the first to examine the longlasting, combined effects of both factors when they are experienced early in life.
The researchers determined that earlylife exercise generally reduced anxious behaviours in adults. It also led to an increase in adult muscle and brain mass. When fed “Western” style diets high in fat and sugar, the mice not only became fatter, but also grew into adults that preferred unhealthy foods.
These findings have recently been published in the journal Physiology and Behavior. To obtain them, the researchers divided the young mice into four groups — those with access to exercise, those without access, those fed a standard, healthy diet and those that ate a Western diet.
Mice started on their diets immediately after weaning (断奶), and continued on them for three weeks, until they reached physical maturity. After an additional eight weeks of “washout”， during which all mice were housed without motion and on the healthy diet, the researchers did behavioral analysis and various measurements.
One of those they measured, leptin, is produced by fat cells. It helps control body weight primarily by lowering the sensation of hunger and also by increasing energy consumption. Earlylife exercise increased adult leptin levels as well as fat mass in adult mice, regardless of the diet they ate.
Previously, the research team found that eating too much fat and sugar as a child can change the gut microbiota (肠道菌群) for life, even if they later eat more healthily. Going forward, the team plans to investigate whether fat or sugar is more responsible for the negative effects they measured in Westerndietfed mice.
Together, both studies offer critical opportunities for health interventions in childhood habits. The findings may be relevant for understanding the potential effects of activity reductions and dietary changes associated with fatness.
【语篇解读】本文是一篇说明文。研究发现，儿童时期的锻炼和健康饮食可以使其成年后拥有更大的大脑和更低的焦虑水平。
1. What is unique about the new study?
A. It involves adults' eating behaviour.
B. It shows key elements for a long life.
C. It stresses separate impacts of exercise and diet.
D. It highlights joint effects of early exercise and diet.
D 细节理解题。根据第二段的内容可知，这项新研究的独特之处在于它首次强调了早期运动和饮食的共同影响。故选D。
2. How did the researchers get the study results?
A. By trial and error.
B. By previous experience.
C. By experimenting on grouped mice.
D. By comparing mice with human beings.
C 细节理解题。根据第四段中的“To obtain them, the researchers divided the young mice into four groups — those with access to exercise, those without access, those fed a standard, healthy diet and those that ate a Western diet.”可知，研究人员通过对老鼠进行分组实验得到研究结果。故选C。
3. What is the main function of leptin?
A. It forms fat cells.
B. It brings down appetite.
C. It stimulates hunger.
D. It limits energy consumption.
B 细节理解题。根据倒数第三段中的“It helps control body weight primarily by lowering the sensation of hunger and also by increasing energy consumption.”可知，leptin(瘦身素)的主要功能是降低食欲。故选B。
4. How does the author look at health interventions in earlylife habits?
A. Favorably. B. Critically.
C. Indifferently. D. Doubtfully.
A 推理判断题。根据最后一段的内容可知，作者认为这两项研究共同提供了对儿童时期的习惯进行健康干预的关键机会，这些发现可能与理解减少活动和饮食变化与肥胖相关的潜在影响有关。因此作者对早期生活习惯的健康干预持支持态度。故选A。
