问题 选择题

下列说法正确的是(  )

A.人体呼吸时,呼出的气体全部是二氧化碳

B.肺适于气体交换的原因是肺泡壁和毛细血管壁均有一层上皮细胞构成

C.人体内二氧化碳的扩散方向是:静脉血→组织细胞→肺泡

D.只有深呼吸时,才能把肺泡的气体全部排除

答案

A、由表格所示可知人体进行呼吸时,吸入的气体不全部是氧气,呼出的气体也不全部是二氧化碳.主要是氮气、氧气、二氧化碳、水等多种气体组成.故不符合题意;

B、肺是最主要的呼吸器官,是进行气体交换的主要场所.肺泡是进行气体交换的主要部位,①肺泡数量多,增加了气体交换的效率;④肺泡外面包绕着丰富的毛细血管和弹性纤维;③肺泡的壁和毛细血管壁都很薄,只有一层上皮细胞构成,这些特点都有利于气体交换.因此肺泡适于气体交换的原因是肺泡壁和毛细血管壁均有一层上皮细胞构成.故符合

题意.

C、人体进行生命活动所需要的能量是由细胞内的有机物在氧气的参与下被分解成二氧化碳时释放出来的,即有机物+氧气→二氧化碳+水+能量;产生的二氧化碳又通过呼吸排出,如图所示:因此人体内二氧化碳的扩散方向是:组织细胞→静脉血→肺泡.故不符合题意;

D、肺容量通俗地说是:肺能装下气体的总量.用力吸气后,无论你怎么努力也无法把肺里的全部气体吐出来,能吐出来那部分是“肺活量”,不能吐出来那部分是“余气量”.所以“肺容量“=肺活量+余气量.因此,深呼吸时,也不能把肺泡的气体全部排除.故不符合题意.

故选:B

阅读理解

When we talk of plants, most of us will think of things that grow from the ground and have green leaves, but there are plants that do not look or act like other plants. Some of these belong to a special class of plants called fungi.

Fungi may appear almost everywhere. They commonly grow in wet places where they call get food and water easily. Because fungi do not have green leaves to make their own food, but fungi must take their food from animals, other plants or water. Some fungi live on dead or rotting(腐烂的)wood, while others grow on living trees or in dirt or moss(苔藓). Mushrooms(蘑茹)are the best-known fungi.

There are many kinds of mushrooms appearing in all shapes and sizes. For example, cauliflower(菜花)mushrooms are found in forests from July to October.They can grow to be as heavy as fifty pounds! They grow at the foot of trees Squirrel’s(松鼠)bread is another kind of wild mushroom Its appearance and use Call explain its name. These fungi look like small golden cakes Squirrels can easily eat them or carry them off to their hole to eat later.

The mushrooms found in food stores are carefully grown by people who know they are safe to eat. People are warned never to touch of taste wild mushrooms because some of them are deadly. Even less dangerous ones cart still make a person very sick..

小题1:Where does Fungi not grow?            .

A.On dry wood

B.In places full of water

C.On living trees

D.Behind houses小题2:Where can Fungi take food?            .

A.From their green leaves

B.From water

C.From rotting wood

D.From people小题3:Squirrel's bread is a kind of            .

A.tree

B.animal

C.food

D.medicine小题4:People are advised not to eat wild fungi because            .

A.it is unfit for main food

B.it may be dangerous to people

C.it doesn't taste so good

D.it's strange smell may do harm to people小题5:The word "fungi" in this passage means

A.草本植物

B.菌类植物

C.食用蘑菇

D.无叶植物

填空题