This Biology quiz is called 'Water Loss in Plants' and it has been written by teachers to help you if you are studying the subject at middle school. Playing educational quizzes is a fabulous way to learn if you are in the 6th, 7th or 8th grade - aged 11 to 14.
It costs only $12.50 per month to play this quiz and over 3,500 others that help you with your school work. You can subscribe on the page at Join Us
This middle school Biology quiz is all about transpiration. Transpiration is the process by which plants transport water upwards against the pull of gravity and it is made possible by water loss due to evaporation. The minerals that a plant needs are carried through it dissolved in water that has come from the ground. Plants have no pump like the heart that could move the water through them and so they have evolved a different method of transporting fluids - transpiration.
Leaves contain spongy and palisade cells. Water on the surface of these evaporates and leaves the leaves by diffusion. Water is then drawn out of the xylem cells within the leaves to replace water lost by this evaporation. The xylem cells form continuous tubes down to the roots and, as water is lost from the leaves, more is drawn up from the roots - rather like when you drink through a drinking straw. Transpiration is continuous and so there is a slow but continuous flow of water through the xylem tubes.
You are expected to know the factors that affect transpiration rate for tests and exams. Most of it is just common sense - anything that changes the speed of water loss to evaporation will affect transpiration - changes in temperature, humidity and the speed of the wind blowing over the leaves. One factor that is less obvious is light. When the light is bright, the stomata open more so that more carbon dioxide can enter the leaves to enable more photosynthesis to take place. Because the stomata are open more, more water can escape from the leaf, increasing transpiration.
There are times when plants need to conserve water in order to survive e.g. when the roots are damaged or water is short. In such situations, gardeners can remove some leaves - fewer leaves mean less transpiration and less water loss. Plants can reduce transpiration for themselves by wilting - you may have noticed this happening for yourself on hot days. Thin needle-like leaves or thick waxy coatings on fleshy leaves and stems are other adaptations to reduce transpiration in plants which live in desert conditions or places where the ground water is frozen for long periods of time.
This quiz is for members only, but you can play our Adaptations for Survival quiz to get an idea what it's all about.
If you're already a subscriber, you can log in here
Or take a look at all of our Biology: Middle School: Grades 6, 7 and 8 quizzes.
Or if you're ready to take the plunge, you can sign up here.