13. Understand and be able to explain the purpose and processes of photosynthesi

Question

13. Understand and be able to explain the purpose and processes of photosynthesis to the extent explained in lecture. Recognize the overall equation for this process. Know what the raw materials and the products are. Know that visible light is used in photosynthesis. Know where the processes of photosynthesis occur in the cell. Understand what happens during both the light reactions and the Calvin Cycle. Know which photosystem produces ATP and which photosystem produces NADPH. Know where and for what the ATP and NADPH produced in the photosystems are used. Know how oxygen is produced during this process. Know where carbon dioxide is used in the process.

14. Understand and be able to explain what pollination is and its role in reproduction.

15. Know the names and characteristics of each class of flowering plants

(Monocot and Eudicot). Be able to recognize what class a plant belongs to by reading a physical description of the plant or plant organ, or by looking at the plant or plant organ.

16. Understand the purpose and function of the digestive system.

Explanation / Answer

Solution 13.

a) Photosynthesis is the process of making food by plants with the help of sunlight. In photosynthesis there is a conversion of light energy into chemical energy, chemical energy is then stored in carbohydrate molecules (like sugar) which are synthesised from carbon dioxide and water.

b) 6CO2       +               6H2O          ---------------       C6H12O6             +           6O2

Carbon dioxide          water                              sugar                         oxygen

c) Raw materials for photosynthesis are water and carbon dioxide.

d) Photosynthesis occurs in the chloroplasts of plant cells.

e) In the Calvin cycle which is light independent process, carbon atoms from CO2 are incorporated into organic molecule and which are then used to build three-carbon sugars. This process is dependent on, ATP and NADPH from the light reactions. Unlike calvin cycle, which take place in stroma, the light reactions take place in the thylakoid membrane.

f) Photosystem I produces NADPH and Photosystem II produces ATP.

g) The ATP and NADPH formed in the light-dependent reactions and are used to make sugars in Calvin cycle.

h) Photosynthesis can be divided into two stages-

Light dependent reaction and the light independent reactions. In the light reactions, an electron is stripped from a water molecule releasing the oxygen and hydrogen atoms. The free oxygen atom combines with another free oxygen atom to produce oxygen gas which is then released.

i) Carbon dioxide is used in spliiting of water in photosynthesis which then produces sugar and oxygen.

Solution 14.

Pollination- it is the process of transfer of pollen grains from male anther to the female stigma of same flower or another flower by suitable vectors like bee, birds etc. It is classified into Biotic (involve transfer by some organism) and Abiotic (no involvement of any organism, for example wind), depending on agent of pollination.

Biotic- further divided into 2 categories, these are self pollination and cross pollination

In Self pollination, if pollen grains are transferred from anther to stigma of same plant then it is called autogamy while, if pollen grains are transferred from anther to stigma of different flower of same plant then it is called geitonogamy.

In Cross pollination, pollen grains are transferred from anther to stigma of different plant. it is also called xenogamy.

As we know, plants are non-motile so they need a medium for transfer of pollen grains to accomplish the purpose of reproduction, so they can increase in number. Pollination fulfill this purpose by helping plants to reproduce by setting seeds.

Solution 15.

Characteristics including physical description of flowering plants belonging to Monocots and eudicots.

examples of monocots- tulip, orchid, bluebell, daffodil, crocus, freesia, amaryllis etc.

examples of eudicots- carnation, poppy, dandelion, chrysanthemum etc.

Solution 16.

Digestion is the process of breakdown of food into small molecules, which are then absorbed into the body with the help of digestive tract (alimentary canal) and acessory organs like teeth, tongue, salivarry gland, pancreas, liver and gall bladder. Digestion of food by disgestive system involves processes like ingestion, propulsion, secretion, absorption and defecation. Primary function and purpose of digestive system is to digest the food and absorbtion of the nutrients from it. Nutrients are then used for various biological processes occuring inside the body and the undigested food material is eliminated through the body via a process called defecation.

Monocots Eudicots have one cotyledons have two cotyledons have parallel leaf venation netlike or reticulate leaf venation Pollen grain has one furrow or aperture Tricolpate pollen grain make around 22% of all angiosperms 7around 5% of all angiosperms Fibrous root system taproot system Vascular bundles are in scattered form (cross-sectional view) Vascular bundles in stem are arranged in ring form (cross-sectional view) Vascular tissue are arranged in form of a ring in root (cross-sectional view) in cross-sectional view, root xylem usually star-shaped, the phloem between arms of star. herbaceous Woody or herbaceous

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