C3 & C4 Plants

By looking at their anatomy,

in C3 plants,

- bundle sheath cells do not contain chloroplasts;
- carbon fixation and Calvin Cycle reactions occur in mesophyll cells
- (and in the presence of oxygen).
- more adapted to environments with more carbon dioxide.


In C4 plants,

- the bundle sheath cells contain chloroplasts;
- carbon is fixed in mesophyll cells too, then transported to bundle sheath cells where
- Calvin Cycle reactions occur in the absence of oxygen.
- more adapted to environments with more oxygen

In both, photosynthesized sugars then enter the plant's vascular system.

C4 have a concentric arrangement of the bundle sheath and mesophyll layer, the bundle sheath is also thicker.

Another difference is their intervenial distances, from one bundle sheath to another you have in C4 only around 4 mesophyll cells but on 3 they are separated by 12.

C3 Photosynthesis : C3 plants.

• Called C3 because the CO2 is first incorporated into a 3-carbon compound.

• Stomata are open during the day.

• RUBISCO, the enzyme involved in photosynthesis, is also the enzyme involved in the uptake of CO2.

• Photosynthesis takes place throughout the leaf.

• Adaptive Value: more efficient than C4 and CAM plants under cool and moist conditions and under normal light because requires less machinery (fewer enzymes and no specialized anatomy)..

• Most plants are C3.

C4 Photosynthesis : C4 plants.

• Called C4 because the CO2 is first incorporated into a 4-carbon compound.

• Stomata are open during the day.

• Uses PEP Carboxylase for the enzyme involved in the uptake of CO2. This enzyme allows CO2 to be taken into the plant very quickly, and then it "delivers" the CO2 directly to RUBISCO for photsynthesis.

• Photosynthesis takes place in inner cells (requires special anatomy called Kranz Anatomy)

• Adaptive Value:
o Photosynthesizes faster than C3 plants under high light intensity and high temperatures because the CO2 is delivered directly to RUBISCO, not allowing it to grab oxygen and undergo photorespiration.

o Has better Water Use Efficiency because PEP Carboxylase brings in CO2 faster and so does not need to keep stomata open as much (less water lost by transpiration) for the same amount of CO2 gain for photosynthesis.

• C4 plants include several thousand species in at least 19 plant families. Example: fourwing saltbush, corn, and many of our summer annual plants.

Examples:
C3----->wheat, barley, potatoes and sugar beet. (most of the plants are C3)
C4----->fourwing saltbush, corn ,many of summer annual plants.
CAM---> cactuses, aloe vera, some orchids and bromeliads (required less water)

Primary & Accessory Pigments

The most significant difference between primary and accessory pigments is that they absorb and give off light at different wavelengths.

When photons of light hit a leaf, they have a specific wavelength. Chlorophyll has a specific wavelength that it can absorb and give off light as. If chlorophyll was the only pigment a plant had, it could only use light that was of this particular wavelength. However, the presence of accessory pigments allows the plant to use light of all wavelengths.

Primary and accessory pigments also vary in color. Chlorophyll is green, while others are different. Carotenoids can be red, yellow or orange. Photosynthetic aquatic organisms like cyanobacteria also have phycobilins.

1. Primary pigments:

primary pigments In photosynthesis, pigments that emit electrons which directly drive the photosynthetic reactions.

In green plants there are two primary pigments,

both of which are forms of Chorophyll a: P680 and P700.

2. Accessory pigments:

a pigment in plants that can absorb light energy and pass the electrons along to the primary pigment which starts the process of photosynthesis.

In the flowering plants (angiosperms),

chlorophylls a and b provide the green color and absorb the light energy needed for photosynthesis.

However, other accessory pigments, such as yellow xanthophylls and orange carotenes are also present in the chloroplasts and collect additional light energy for photosynthesis.

All plants, algae, and cyanobacteria which photosynthesize contain chlorophyll "a".

A second kind of chlorophyll is chlorophyll "b", which occurs only in green algae and in the plant.

Carotenoids act as \"SHIELD PIGMENTS\" as they are located over the chlorophylls thus protecting them from photo-oxidation and photo-bleaching. (antioxidants)

Phycobilins are water-soluble pigments, and are therefore found in the cytoplasm, or in the stroma of the chloroplast. They occur only in Cyanobacteria and Rhodophyta.

Bonded to certain water-soluble proteins, ‘Phycobiliproteins’ then pass the light energy to chorophyll for photosynthesis.

The phycobilins are especially efficient at absorbing red, orange, yellow and green light, wavelengths which are not well absorbed by chlorophyll a. Organisms growing in shallow waters tend to contain phycobilins that can capture yellow/red light, while those at greater depth often contain more of the phycobilins that can capture green light, which is relatively more abundant there.

空腹不能吃的食物

牛奶、酸奶、豆浆
这些食物中含有大量的蛋白质，空腹饮用，蛋白质将“被迫”转化为热能消耗掉，起不到营养滋补作用。正确的饮用方法是与饼干、糕点等含面粉的食品同食，或餐后两小时再喝，或睡前喝。

酒
空腹饮酒会刺激胃黏膜，久之易引起胃炎、胃溃疡等疾病。另外，人空腹时本身血糖水平就较低，此时饮酒很容易出现低血糖，脑组织会因缺乏葡萄糖的供应而发生功能性障碍，出现头晕、心悸、出冷汗及饥饿感，严重者会发生低血糖昏迷。

茶
空腹饮茶会稀释胃液，降低消化功能，还会引起“茶醉”，表现为心慌、头晕、头痛、乏力、站立不稳等。

糖
糖是一种极易消化吸收的食品，空腹大量吃糖，人体短时间内不能分泌足够的胰岛素（insulin）来维持血糖的正常水平，会使血液中的血糖骤然升高，实属不利。而且糖属酸性食品，空腹吃糖还会破坏机体内的酸碱平衡和各种微生物的平衡，对健康有害。

柿子、番茄
它们含有较多的果胶、单宁酸，上述物质与胃酸发生化学反应生成难以溶解的凝胶块，易形成胃结石。

香蕉
香蕉中含有较多的镁元素，空腹吃香蕉会使人体中的镁骤然升高而破坏血液中的镁钙平衡，对心血管产生抑制作用，不利于身体健康。

山楂、桔子
含有大量的有机酸如果酸、山楂酸、枸橼酸等，空腹食用会使胃内酸度猛增，对胃黏膜造成不良刺激，可导致腹胀、嗳气、返酸，甚至加重胃炎和胃溃疡。

大蒜
大蒜含有强烈辛辣的大蒜素，空腹食蒜会对胃黏膜、肠壁造成强烈的刺激，引起胃肠痉挛、绞痛。

白薯
白薯中含有单宁酸和胶质，会刺激胃壁分泌更多胃酸，引起烧心、嗳气等不适感。

冷饮
空腹时暴饮各种冷冻食品，会刺激胃肠发生痉挛，久之将导致各种酶促化学反应失调，诱发肠胃疾病；女性月经期间还会使月经发生紊乱。

咖啡
刺激胃酸分泌

食物相忌

1》不能一起吃的食物

红薯和柿子——会得结石

鸡蛋和糖精——容易中毒

洋葱和蜂蜜——伤害眼睛

豆腐和蜂蜜——引发耳聋

萝卜和木耳——皮肤发炎

芋头和香蕉——腹胀

花生和黄瓜——伤害肾脏

牛肉和栗子——引起呕吐

兔肉和芹菜——容易脱发

螃蟹和柿子——腹泻

鲤鱼和甘草——会中毒



2》20种不能一起吃的食物

1. 猪肉*菱角——肚子痛

2. 牛肉*栗子——引起呕吐

3. 羊肉*西瓜——伤元气

4. 狗肉*绿豆——会中毒

5. 兔肉*芹菜——脱发

6. 鸡肉*芹菜——伤元气

7. 鹅肉*鸡蛋——伤元气

8. 甲鱼*苋菜——会中毒

9. 鲤鱼*甘草——会中毒

10. 螃蟹*柿子——腹泻

11. 白酒*柿子——会胸闷

12. 红薯*柿子——会得结石

13. 糖精（片）*鸡蛋——会中毒、重则死亡

14. 红塘*皮蛋——会中毒

15. 洋葱*蜂蜜——伤眼睛

16. 豆腐*蜂蜜——耳聋

17. 萝卜*木耳——得皮炎

18. 马铃薯*香蕉——面部生斑

19. 芋头*香蕉——腹涨

20. 花生*黄瓜——会伤身



3》21种食物不能一起吃

1.猪肉菱角若共食,肚子疼痛不好受.

2.牛肉栗子一起吃,食后就会发呕吐.

3.羊肉滋补大有用,若遇西瓜定相侵.

4.狗肉滋补需注意,若遇绿豆定伤身.

5.兔肉芹菜本不合,同食之后头发脱.

6.鸡肉芹菜也相忌,同食就会伤元气.

7.鹅肉鸡蛋不同窝,一同入胃伤身体.

8.鲤鱼甘草性相反,兼食而之定伤身.

9.黄鳝皮蛋皆佳肴,不可同桌结伴行.

10.鸡蛋若遇消炎片,同室操戈两相争.

11.鸡蛋糖精更相克,同食中毒更伤身.

12.柿子红薯若同吃,体内结石易形成.

13.柿子螃蟹也相背,同食之后会腹泻.

14.柿子白酒更不合,食后使你心发闷.

15.豆腐蜂蜜伴着吃,味道虽好耳要聋.

16.洋葱蜂蜜也不合,同食就会伤眼睛.

17.香蕉芋头本不合,同时入胃腹胀痛.

18.香蕉相克马铃薯,同食面部要起斑.

19.黄瓜生熟都可以,进食之际忌花生.

20.萝卜木耳不同食,食了容易生皮炎.

21.萝卜水果更相背,甲状腺肿会诱发.



4》这些食物不能一起吃

吃，真是一门很大的学问。各种美食之间，常常相冲相撞。

如果将这些相冲撞的食物同食，不但不会得到美的享受，

反而会损害身体，真是不可不防呀！

啤酒忌白酒啤酒中含有大量的二氧化碳，容易挥发，

如果与白酒同饮，就会带动酒精渗透。

有些朋友常常是先喝了啤酒再喝白酒，或是先喝白酒再喝

啤酒，这样做实属不当。想减少酒精在体内的驻留，最好是

多饮一些水，以助排尿。

酒精忌咖啡酒中含有的酒精，具有兴奋作用，而咖啡所含

咖啡因，同样具有较强的兴奋作用。两者同饮，对人产生的

刺激甚大。如果是在心情紧张或是心情烦躁时这样饮用，会

加重紧张和烦躁情绪；若是患有神经性头痛的人如此饮用，

会立即引发病痛；若是患有经常性失眠症的人，会使病情恶

化；如果是心脏有问题，或是有阵发性心跳过速的人，将咖啡

与酒同饮，其后果更为不妙，很可能诱发心脏病。一旦将二者

同时饮用，应饮用大量清水或是在水中加入少许葡萄糖和食

盐喝下，可以缓解一下不适症状。

解酒忌浓茶有些朋友在醉酒后，饮用大量的浓茶，试图解酒。

殊不知茶叶中含有的咖啡碱与酒精结合后，会产生不良的后果，

不但起不到解酒的作用，反而会加重醉酒的痛苦。

鲜鱼忌美酒含维生素 D高的食物有鱼、鱼肝、鱼肝油等，吃

此类食物饮酒，会减少人对维生素 D吸收量的6—7成。人们常

常是鲜鱼佐美酒，殊不知这种吃法却丢了上好的营养成分。

虾蟹类忌维生素虾、蟹等食物中含有五价砷化合物，如果与含

有维生素 C的生果同食，会令砷发生变化，转化成三价砷，也就

是剧毒的“砒霜”，危害甚大。长期食用，会导致人体中毒，免疫

力下降。

牛奶煮沸时忌加糖牛奶中所含的赖氨酸在高温下与果糖结合

成果糖基赖氨酸，不易被人体消化。食用后会出现肠胃不适、

呕吐、腹泻病症，影响健康。

菠菜忌豆腐菠菜中所含的草酸，与豆腐中所含的钙产生草酸

钙凝结物，阻碍人体对菠菜中的铁质和豆腐中蛋白的吸收。

牛奶忌朱古力朱古力中含有草酸，与牛奶中所含的蛋白质、

钙质结合后产生草酸钙。一些人食用后会发生腹泻现象。



5》哪些食物不能和牛奶一起吃

经常喝牛奶对健康好处多多，但食物总有互相抵触发生反应

的时候，在日常生活中我们要留点神，记住哪些食物不可一起

食用，以免危害你的身体健康，下面介绍一下牛奶和哪些食物

不可同时服用？

<<橘子>>在喝牛奶前后1小时左右，不宜吃橘子。因为牛奶中

所含的蛋白质与橘子中的果酸相遇后，就会发生凝固，从而影

响人体对牛奶的消化与吸收，在服用牛奶这个时间段里同样

不宜食用其他酸性水果。

<<果汁>>牛奶中的蛋白质80％为酪蛋白，牛奶的酸碱度在

4.6以下时，大量的酪蛋白便会发生凝集、沉淀，难以消化吸收，

严重者还可能导致消化不良或腹泻。所以牛奶中不宜添加果汁

等酸性饮料。

<<糖>>牛奶中含有的赖氨酸在加热条件下能与果糖反应，生成

有毒的果糖基赖氨酸，有害于人体。鲜牛奶在煮沸时不要加糖，

煮好牛奶后等牛奶稍凉以后再加糖。

<巧克力>>牛奶含有丰富蛋白质和钙，而巧克力含有草酸，两者

同食会结合成不溶性草酸钙，极大影响钙的吸收。甚至出现

头发干枯、腹泻、生长缓慢等现象。

<<药>>有人喜欢用牛奶代替白开水服药，其实，牛奶会明显地

影响人体对药物的吸收。由于牛奶容易在药物的表面形成一个

覆盖膜，使奶中的钙、镁等矿物质与药物发生化学反应，形成

非水溶性物质，从而影响药效的释放及吸收。因此，在服药前后

1小时也不要喝奶。



6》哪些食物相克

以下相克食物2小时内不可同吃，望大家谨记。

1、鸡蛋忌糖精┄┄同食中毒、死亡

2、豆腐忌蜂蜜┄┄同食耳聋

3、海带忌猪血┄┄同食便秘

4、土豆忌香蕉┄┄同食生雀斑

5、牛肉忌红糖┄┄同食胀死人

6、狗肉忌黄鳝┄┄同食则死

7、羊肉忌田螺┄┄同食积食腹胀

8、芹菜忌兔肉┄┄同食脱头发

9、番茄忌绿豆┄┄同食伤元气

10、螃蟹忌柿子┄┄同食腹泻

11、鹅肉忌鸭梨┄┄同食伤肾脏

12、洋葱忌蜂蜜┄┄同食伤眼睛

13、黑鱼忌茄子┄┄同食肚子痛

14、甲鱼忌苋菜┄┄同食中毒

15、皮蛋忌红糖┄┄同食作呕

16、人参忌萝卜┄┄同食积食滞气

17、白酒忌柿子┄┄同食心闷