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1、Toefl iBT Practice Test TPO 5 Reading Section 1No. of Questions: 14Time: 20 minutesBegin Test5If you cannot see the timer or if you cannot set the timer, youll need to install flash player. Click here to download and install adobe flash player.Set the timer to “20:00” before doing the test.Minerals

2、and PlantsResearch has shown that certain minerals are required by plants for normal growth and development The soil is the source of these minerals which are absorbed by the plant with the water from the soil Even nitrogen, which is a gas in its elemental state, is normally absorbed from the soil a

3、s nitrate ions Some soils are notoriously deficient in micro nutrients and are therefore unable to support most plant life So-called serpentine soils, for example, are deficient in calcium, and only plants able to tolerate low levels of this mineral can survive In modern agriculture, mineral depleti

4、on of soils is a major concern, since harvesting crops interrupts the recycling of nutrients back to the soil.Mineral deficiencies can often be detected by specific symptoms such as chlorosis loss of chlorophyll resulting in yellow or white leaf tissue), necrosis (isolated dead patches), anthocyanin

5、 formation (development of deep red pigmentation of leaves or stem), stunted growth, and development of woody tissue in an herbaceous plant Soils are most commonly deficient in nitrogen and phosphorus. Nitrogen-deficient plants exhibit many of the symptoms just described Leaves develop chlorosis, st

6、ems are short and slender, and anthocyanin discoloration occurs on stems, petioles, and lower leaf surfaces Phosphorus- deficient plants are often stunted, with leaves turning a characteristic dark green, often with the accumulation of anthocyanin. Typically, older leaves are affected first as the p

7、hosphorus is mobilized to young growing tissue Iron deficiency is characterized by chlorosis between veins in young leaves.Much of the research on nutrient deficiencies is based on growing plants hydroponically. that is. in soilless liquid nutrient solutions This technique allows researchers to crea

8、te solutions that selectively omit certain nutrients and then observe the resulting effects on the plants Hydroponics has applications beyond basic research, since it facilitates the growing of greenhouse vegetables during winter. Aeroponics, a technique in which plants are suspended and the roots m

9、isted with a5Question 1 of 14According to paragraph 1, what is true of plants thatcan grow in serpentine soils?They absorb micronutrients unusually well.They require far less calcium than most plants doThey are able to absorb nitrogen in its elemental state.They are typically crops raised for foodPa

10、ragraph 1 is marked with Minerals and Plants Research has shown that certain minerals are required by plants for normal growth and development The soil is the source of these minerals which are absorbed by the plant with the water from the soil Even nitrogen, which is a gas in its elemental state, i

11、s normally absorbed from the soil as nitrate ions Some soils are notoriously deficient in micro nutrients and are therefore unable to support most plant life So-called serpentine soils, for example, are deficient in calcium, and only plants able to tolerate low levels of this mineral can survive In

12、modern agriculture, mineral depletion of soils is a major concern, since harvesting crops interrupts the recycling of nutrients back to the soil.Mineral deficiencies can often be detected by specific symptoms such as chlorosis loss of chlorophyll resulting in yellow or white leaf tissue), necrosis (

13、isolated dead patches), anthocyanin formation (development of deep red pigmentation of leaves or stem), stunted growth, and development of woody tissue in an herbaceous plant Soils are most commonly deficient in nitrogen and phosphorus. Nitrogen-deficient plants exhibit many of the symptoms just des

14、cribed Leaves develop chlorosis, stems are short and slender, and anthocyanin discoloration occurs on stems, petioles, and lower leaf surfaces Phosphorus- deficient plants are often stunted, with leaves turning a characteristic dark green, often with the accumulation of anthocyanin. Typically, older

15、 leaves are affected first as the phosphorus is mobilized to young growing tissue Iron deficiency is characterized by chlorosis between veins in young leaves.Much of the research on nutrient deficiencies is based on growing plants hydroponically. that is. in soilless liquid nutrient solutions This t

16、echnique allows researchers to create solutions that selectively omit certain nutrients and then observe the resulting effects on the plants Hydroponics has applications beyond basic research, since it facilitates the growing of greenhouse vegetables during winter. Aeroponics, a technique in which p

17、lants are suspended and the roots misted with a5Question 2 of 14The word 【exhibit】 in the passage is closest in meaning tofight offshowcausespreadMinerals and PlantsResearch has shown that certain minerals are required by plants for normal growth and development The soil is the source of these miner

18、als which are absorbed by the plant with the water from the soil Even nitrogen, which is a gas in its elemental state, is normally absorbed from the soil as nitrate ions Some soils are notoriously deficient in micro nutrients and are therefore unable to support most plant life So-called serpentine s

19、oils, for example, are deficient in calcium, and only plants able to tolerate low levels of this mineral can survive In modern agriculture, mineral depletion of soils is a major concern, since harvesting crops interrupts the recycling of nutrients back to the soil.Mineral deficiencies can often be d

20、etected by specific symptoms such as chlorosis loss of chlorophyll resulting in yellow or white leaf tissue), necrosis (isolated dead patches), anthocyanin formation (development of deep red pigmentation of leaves or stem), stunted growth, and development of woody tissue in an herbaceous plant Soils

21、 are most commonly deficient in nitrogen and phosphorus. Nitrogen-deficient plants 【 exhibit 】 many of the symptoms just described Leaves develop chlorosis, stems are short and slender, and anthocyanin discoloration occurs on stems, petioles, and lower leaf surfaces Phosphorus-deficient plants are o

22、ften stunted, with leaves turning a characteristic dark green, often with the accumulation of anthocyanin. Typically, older leaves are affected first as the phosphorus is mobilized to young growing tissue Iron deficiency is characterized by chlorosis between veins in young leaves.Much of the researc

23、h on nutrient deficiencies is based on growing plants hydroponically. that is. in soilless liquid nutrient solutions This technique allows researchers to create solutions that selectively omit certain nutrients and then observe the resulting effects on the plants Hydroponics has applications beyond

24、basic research, since it facilitates the growing of greenhouse vegetables during winter. Aeroponics, a technique in which plants are suspended and the roots misted with a5Question 3 of 14According to paragraph 2, which of the following symptoms occurs in phosphorus-deficient plants but not in plants

25、 deficient in nitrogen or iron?Chlorosis on leavesChange in leaf pigmentation to a dark shade of greenShort, stunted appearance of stemsReddish pigmentation on the leaves or stemParagraph 2 is marked with Minerals and PlantsResearch has shown that certain minerals are required by plants for normal g

26、rowth and development The soil is the source of these minerals which are absorbed by the plant with the water from the soil Even nitrogen, which is a gas in its elemental state, is normally absorbed from the soil as nitrate ions Some soils are notoriously deficient in micro nutrients and are therefo

27、re unable to support most plant life So-called serpentine soils, for example, are deficient in calcium, and only plants able to tolerate low levels of this mineral can survive In modern agriculture, mineral depletion of soils is a major concern, since harvesting crops interrupts the recycling of nut

28、rients back to the soil. Mineral deficiencies can often be detected by specific symptoms such as chlorosis loss of chlorophyll resulting in yellow or white leaf tissue), necrosis (isolated dead patches), anthocyanin formation (development of deep red pigmentation of leaves or stem), stunted growth,

29、and development of woody tissue in an herbaceous plant Soils are most commonly deficient in nitrogen and phosphorus. Nitrogen- deficient plants exhibit many of the symptoms just described Leaves develop chlorosis, stems are short and slender, and anthocyanin discoloration occurs on stems, petioles,

30、and lower leaf surfaces Phosphorus-deficient plants are often stunted, with leaves turning a characteristic dark green, often with the accumulation of anthocyanin. Typically, older leaves are affected first as the phosphorus is mobilized to young growing tissue Iron deficiency is characterized by ch

31、lorosis between veins in young leaves.Much of the research on nutrient deficiencies is based on growing plants hydroponically. that is. in soilless liquid nutrient solutions This technique allows researchers to create solutions that selectively omit certain nutrients and then observe the resulting e

32、ffects on the plants Hydroponics has applications beyond basic research, since it facilitates the growing of greenhouse vegetables during winter. Aeroponics, a technique in which plants are suspended and the roots misted with a5Question 4 of 14According to paragraph 2, a symptom of iron deficiency i

33、s the presence in young leaves ofdeep red discoloration between the veinswhite or yellow tissue between the veinsdead spots between the veinscharacteristic dark green veinsParagraph 2 is marked with Minerals and PlantsResearch has shown that certain minerals are required by plants for normal growth

34、and development The soil is the source of these minerals which are absorbed by the plant with the water from the soil Even nitrogen, which is a gas in its elemental state, is normally absorbed from the soil as nitrate ions Some soils are notoriously deficient in micro nutrients and are therefore una

35、ble to support most plant life So-called serpentine soils, for example, are deficient in calcium, and only plants able to tolerate low levels of this mineral can survive In modern agriculture, mineral depletion of soils is a major concern, since harvesting crops interrupts the recycling of nutrients

36、 back to the soil. Mineral deficiencies can often be detected by specific symptoms such as chlorosis loss of chlorophyll resulting in yellow or white leaf tissue), necrosis (isolated dead patches), anthocyanin formation (development of deep red pigmentation of leaves or stem), stunted growth, and de

37、velopment of woody tissue in an herbaceous plant Soils are most commonly deficient in nitrogen and phosphorus. Nitrogen- deficient plants exhibit many of the symptoms just described Leaves develop chlorosis, stems are short and slender, and anthocyanin discoloration occurs on stems, petioles, and lo

38、wer leaf surfaces Phosphorus-deficient plants are often stunted, with leaves turning a characteristic dark green, often with the accumulation of anthocyanin. Typically, older leaves are affected first as the phosphorus is mobilized to young growing tissue Iron deficiency is characterized by chlorosi

39、s between veins in young leaves.Much of the research on nutrient deficiencies is based on growing plants hydroponically. that is. in soilless liquid nutrient solutions This technique allows researchers to create solutions that selectively omit certain nutrients and then observe the resulting effects

40、 on the plants Hydroponics has applications beyond basic research, since it facilitates the growing of greenhouse vegetables during winter. Aeroponics, a technique in which plants are suspended and the roots misted with a5Question 5 of 14The word 【facilitates】 in the passage is closest in meaning to

41、slows downaffectsmakes easierfocuses onMinerals and PlantsResearch has shown that certain minerals are required by plants for normal growth and development The soil is the source of these minerals which are absorbed by the plant with the water from the soil Even nitrogen, which is a gas in its eleme

42、ntal state, is normally absorbed from the soil as nitrate ions Some soils are notoriously deficient in micro nutrients and are therefore unable to support most plant life So-called serpentine soils, for example, are deficient in calcium, and only plants able to tolerate low levels of this mineral ca

43、n survive In modern agriculture, mineral depletion of soils is a major concern, since harvesting crops interrupts the recycling of nutrients back to the soil.Mineral deficiencies can often be detected by specific symptoms such as chlorosis loss of chlorophyll resulting in yellow or white leaf tissue

44、), necrosis (isolated dead patches), anthocyanin formation (development of deep red pigmentation of leaves or stem), stunted growth, and development of woody tissue in an herbaceous plant Soils are most commonly deficient in nitrogen and phosphorus. Nitrogen-deficient plants exhibit many of the symp

45、toms just described Leaves develop chlorosis, stems are short and slender, and anthocyanin discoloration occurs on stems, petioles, and lower leaf surfaces Phosphorus- deficient plants are often stunted, with leaves turning a characteristic dark green, often with the accumulation of anthocyanin. Typ

46、ically, older leaves are affected first as the phosphorus is mobilized to young growing tissue Iron deficiency is characterized by chlorosis between veins in young leaves.Much of the research on nutrient deficiencies is based on growing plants hydroponically. that is. in soilless liquid nutrient sol

47、utions This technique allows researchers to create solutions that selectively omit certain nutrients and then observe the resulting effects on the plants Hydroponics has applications beyond basic research, since it【 facilitates 】 the growing of greenhouse vegetables during winter. Aeroponics, a tech

48、nique in which plants are suspended and the roots5Question 6 of 14According to paragraph 3, what is the advantage of hydroponics for research on nutrient deficiencies in plants?It allows researchers to control what nutrients a plant receives.It allows researchers to observe the growth of alarge numb

49、er of plants simultaneously.It is possible to directly observe the roots of plants.It is unnecessary to keep misting plants with nutrient solutions.Paragraph 3 is marked with Minerals and PlantsResearch has shown that certain minerals are required by plants for normal growth and development The soil

50、 is the source of these minerals which are absorbed by the plant with the water from the soil Even nitrogen, which is a gas in its elemental state, is normally absorbed from the soil as nitrate ions Some soils are notoriously deficient in micro nutrients and are therefore unable to support most plan

51、t life So-called serpentine soils, for example, are deficient in calcium, and only plants able to tolerate low levels of this mineral can survive In modern agriculture, mineral depletion of soils is a major concern, since harvesting crops interrupts the recycling of nutrients back to the soil.Minera

52、l deficiencies can often be detected by specific symptoms such as chlorosis loss of chlorophyll resulting in yellow or white leaf tissue), necrosis (isolated dead patches), anthocyanin formation (development of deep red pigmentation of leaves or stem), stunted growth, and development of woody tissue

53、 in an herbaceous plant Soils are most commonly deficient in nitrogen and phosphorus. Nitrogen-deficient plants exhibit many of the symptoms just described Leaves develop chlorosis, stems are short and slender, and anthocyanin discoloration occurs on stems, petioles, and lower leaf surfaces Phosphor

54、us- deficient plants are often stunted, with leaves turning a characteristic dark green, often with the accumulation of anthocyanin. Typically, older leaves are affected first as the phosphorus is mobilized to young growing tissue Iron deficiency is characterized by chlorosis between veins in young

55、leaves. Much of the research on nutrient deficiencies is based on growing plants hydroponically. that is. in soilless liquid nutrient solutions This technique allows researchers to create solutions that selectively omit certain nutrients and then observe the resulting effects on the plants Hydroponi

56、cs has applications beyond basic research, since it facilitates the growing of greenhouse vegetables during winter. Aeroponics, a technique in which plants are suspended and the roots misted with a5Question 7 of 14The word 【suspended】 in the passage is closest in meaning togrownprotectedspread outhu

57、ngMinerals and PlantsResearch has shown that certain minerals are required by plants for normal growth and development The soil is the source of these minerals which are absorbed by the plant with the water from the soil Even nitrogen, which is a gas in its elemental state, is normally absorbed from

58、 the soil as nitrate ions Some soils are notoriously deficient in micro nutrients and are therefore unable to support most plant life So-called serpentine soils, for example, are deficient in calcium, and only plants able to tolerate low levels of this mineral can survive In modern agriculture, mine

59、ral depletion of soils is a major concern, since harvesting crops interrupts the recycling of nutrients back to the soil.Mineral deficiencies can often be detected by specific symptoms such as chlorosis loss of chlorophyll resulting in yellow or white leaf tissue), necrosis (isolated dead patches), anthoc