nutrition and transport in flowering plants

Question 1

what is autotrophic nutrition

Answer 1

In autotrophic nutrition the organism builds up the organic molecules that it requires from simple inorganic molecules, such as carbon dioxide and water. This process requires an energy source.

Question 2

what is photoautotroph

Answer 2

If the energy source is light energy, the type of nutrition is called photoautotrophic nutrition.
Green plants are photoautotrophs. They carry out photosynthesis.

Question 3

what are chemoautotrophs

Answer 3

If the energy source comes from specific chemical reactions that the organisms are able to catalyse, these non-green organisms are called chemoautotrophs.

Question 4

what is heterotrophic nutrition

Answer 4

Animals cannot manufacture organic molecules from inorganic molecules. They depend directly or indirectly on organic molecules made by photosynthetic plants. The way animals feed is called heterotrophic nutrition.

Question 5

what is needed for photosynthesis to take place

Answer 5

For photosynthesis to take place, light energy, water, carbon dioxide and chlorophyll are required.

Question 6

describer the process of photosynthesis

Answer 6

Photosynthesis is the process whereby carbohydrates are synthesised from carbon dioxide and water by green plants using energy from sunlight which is absorbed by chlorophyll.

Question 7

how does the plant obtain ATP

Answer 7

Light energy is absorbed by the green pigment chlorophyll in the chloroplasts of leaf cells. This light energy is converted to chemical energy in the form of ATP molecules. The ATP molecules are channelled to the light-independent stage.

Question 8

what is photolysis of water

Answer 8

Light energy is also used to split water molecules into oxygen gas and hydrogen ions. This process is called photolysis of water.

Question 9

after water molecules is split, what is the hydrogen used for

Answer 9

The hydrogen ions are used to reduce NADP+ (nicotinamide adenine dinucleotide phosphate) to NADPH.

Question 10

what does NADPH do

Answer 10

NADPH is then used in the light-independent stage to reduce carbon dioxide to glucose.
(reduce as in changing a substance into smt)

Question 11

what does the process of reduction by NADPH require

Answer 11

This process of reduction requires chemical energy in the form of ATP molecules from the light-dependent stage.

Question 12

y is the light-independent stage temperature dependent

Answer 12

Enzymes are needed in the light-independent stage, thus it is temperature dependent.

Question 13

what is the thylakoid membrane

Answer 13

the membrane surrounding the thylakoid. It’s where the photosynthetic reactions occur.

Question 14

Light-dependent stage vs Light-independent stage
what is the process

Answer 14

LD - photosynthesis
LI - calvin cycle

Question 15

Light-dependent stage vs Light-independent stage
Site of occurrence in chloroplast

Answer 15

LD - thylakoid membrane
LI - stroma

Question 16

Light-dependent stage vs Light-independent stage
requirement for their process

Answer 16

LD - Light energy, water, chlorophyll
LI - Carbon dioxide, chemical energy (ATP molecules), hydrogen ions, enzymes

Question 17

Light-dependent stage vs Light-independent stage
temperature sensitive?

Answer 17

LD - no
LI - yes

Question 18

Light-dependent stage vs Light-independent stage
products formed from their processes

Answer 18

LD - Oxygen gas, hydrogen ions, chemical energy (ATP molecules)
LI -Glucose

Question 19

what is cellular respiration in the plant

Answer 19

Glucose is used for cellular respiration in leaf cells, releasing chemical energy in the form of ATP molecules for anabolic processes, protoplasm build-up, cell division and active transport.

Question 20

what is used to make the cellulose cell wall

Answer 20

Glucose is used to make the cellulose cell wall.

Question 21

what happens to the extra glucose then

Answer 21

Excess glucose is converted to sucrose which is transported to storage organs (stem and root tubers) to be stored as starch.

Question 22

how do leaves get ATP at night

Answer 22

During the day when the rate of photosynthesis is very high, sugar that accumulates in the leaves is converted into starch for temporary storage in the leaves. At night when photosynthesis stops, starch is reconverted into simple sugars to be used in cellular respiration. (Starch is digested by amylase to maltose and maltose is digested by maltase to glucose.)

Question 22

how to destarch a plant

Answer 22

1. leave it in darkness for 2-3 days
2. In darkness, starch in the leaves will be hydrolysed to sugars and carried away to other parts of the plant.
3. One of the leaves should be tested before the experiment begins to ensure that no starch is present.

Question 23

how to test whether photosynethesis has occured

Answer 23

pout brown iodine. if iodine turn blue-black, starch present

Question 24

at high light intensity how does temperature affect the rate of photosynthesis

Answer 24

temperature rise increases the rate of photosynthesis but at 35degs, the temeprature denatures the enzymes and the rate of p[hotoynsthesis reduces

Question 25

what could the limit on the increase on the rate of photosynthesis be due to

Answer 25

 all available **chlorophyll** in chloroplasts are **fully utilised** in light absorption **(light saturation point).**  there is **not enough carbon dioxide** in the air **to be reduced** by an increased supply of **NADPH** produced in the light-dependent stage **(carbon dioxide concentration is limiting factor).**  **Low temperature** is restricting the rate of the light-independent stage **(temperature is limiting factor).**

Question 26

importance of photosynthesis

Answer 26

1. **light energy** is transformed to **chemical energy** which is stored within carbohydrate molecules. From carbohydrates, fats and proteins formed. These become food for animals that depend **directly or indirectly** on plants. 2. Photosynthesis helps to **remove carbon dioxide** from the air. It also **produces oxygen** that is used by living organisms in **respiration.**

Question 27

4 parts of a green leaf

Answer 27

**lamina**(leaf blade) large flat surface compared to its volume. **petiole**(leaf stalk) holds the lamina away from the stem. **midrib** (main vein) is a continuation of the petiole into the leaf. Network of **veins** containing **vascular bundles** branches from the midrib.

Question 28

what is the epidermis in structure of the leaf

Answer 28

The epidermis is a **single layer of cells** on the **upper** and **lower** surfaces of the leaf. The epidermis is covered by a **waxy, waterproof** layer, called the **cuticle**, that protects the leaf and prevents **excessive evaporation** of water.

Question 29

what is the tissue between the upper and lower epidermis is called

Answer 29

The tissue between the upper and lower epidermis is called **mesophyll.**

Question 29

upper vs lower mesophyll

Answer 29

 The upper, **palisade** mesophyll, with **elongated cells** and **many chloroplasts**  The lower, **spongy** mesophyll, that vary in shape and **fit loosely together**, leaving many **air spaces** in between them

Question 30

what does the vein of a leaf contain

Answer 30

The vein of the leaf contains **vascular bundles.**

Question 31

what does the vascular bundle contain

Answer 31

 **Xylem vessels** transport _water and dissolved mineral salts_ **to** mesophyll cells.  **Phloem sieve tubes** transport _sugars_ **from** mesophyll cells to other parts of the plant.

Question 32

what is in the leaf epidermis

Answer 32

In the leaf epidermis there are structures called **stomata**

Question 33

what is the stoma surrounded by

Answer 33

A stoma is surrounded by a pair of **guard cells**. In most dicotyledons, stomata occur only in the **lower epidermis.**

Question 34

guard cells shape and what do they contain

Answer 34

The guard cells are **bean-shaped** in surface view and they contain **chloroplasts.**

Question 35

when does the stomata of most species tend to open

Answer 35

The stomata of most species tend to **open in the light** and **close in the dark.**

Question 36

y do guard cells become turgid

Answer 36

In the light, _potassium ions (K+)_ are **actively** accumulated in the guard cells, thus the water potential is **more negative** within the guard cells than neighbouring cells. Water molecules from other cells enter the guard cells by **osmosis** _across the selectively permeable cell membrane_. The **turgor pressure** inside the guard cells **increases.**

Question 37

how do the guard cells close

Answer 37

In darkness, **potassium ions** leave the guard cells, thus the water potential in the guard cells becomes **less negative** than that in neighbouring cells. Water molecules **leave** the guard cells by **osmosis** across the _selectively permeable cell membrane_. **Turgor pressure** inside the guard cells **decreases**. The guard cells **straighten up** and _close the stomatal pore._

Question 38

how do the guard cells open

Answer 38

**Cellulose microfibrils** in the walls _resist stretching and compression._ **radial orientation** of the microfibrils causes the cells to **increase in length more than width** when turgor increases. The two guard cells are **attached at their tips**, so the increase in length causes **buckling.**

Question 38

how to test the rate of photosynthesis quantitatively

Answer 38

The **rate of photosynthesis** can be measured **quantitatively** by counting the **number of air bubbles** evolved from the aquatic plant over a period of 5 minutes.

Question 39

how are lipids formed

Answer 39

Lipids are formed from fatty acids and glycerol.

Question 40

how to vary light intensity for rate of photosynthesis tests

Answer 40

Lamp at varying distances from the plant

Question 40

factors that need to be kept constant in an aquatic plants rate of photosynthesis test

Answer 40

- Watts of light bulb - Concentration of sodium hydrogencarbonate solution - Temperature of water bath

Question 41

how does carbon dioxide enter the leaf

Answer 41

In daylight when photosynthesis occurs, carbon dioxide in the leaf is **rapidly used up**. Carbon dioxide concentration in the leaf becomes **lower** than that in atmospheric air, thus a **diffusion gradient** exists. **Carbon dioxide** diffuses into the systems of **air spaces** in the leaf. The surfaces of the **mesophyll cells** are covered by a **thin film of water**, so that carbon dioxide can **dissolve** in it.

Question 42

Most plants have numerous leaves that have a large surface area. function

Answer 42

Allows **maximum absorption** of light energy by chlorophyll in chloroplasts. Facilitates inward diffusion of **carbon dioxide** and enables **light** to reach all mesophyll cells.

Question 43

Epidermis having Thick external walls and with a waxy cuticle on outer surface. function

Answer 43

**Protects** leaf tissue from invasion by **fungal parasites** and from **excessive water loss.**

Question 43

Petiole holds lamina away from stem. fucntion

Answer 43

Holds leaf in position to absorb **maximum** light energy.

Question 44

Spongy mesophyll has Mostly spherical cells with some chloroplasts and large interconnecting **air spaces** in between them.

Answer 44

Facilitates **gaseous exchange** of carbon dioxide and oxygen by diffusion.

Question 44

Stomata has Pores in the leaf epidermis between two guard cells; changes in **turgidity** of guard cells cause them to open or close.

Answer 44

Open in the light; allow diffusion of carbon dioxide into the leaf and oxygen out of the leaf.

Question 45

Palisade mesophyll has **Elongated cells** closely packed together with numerous chloroplasts.

Answer 45

**Maximise** light energy absorbed by **chlorophyll** in the chloroplasts.

Question 46

Vascular bundles contain xylem and phloem.

Answer 46

**Xylem vessels** deliver water and dissolved mineral salts to mesophyll cells. **Phloem sieve tubes** transport sugars away from the leaf.

Question 47

what are the The mineral elements needed by plants are absorbed from the soil in the form of salts.

Answer 47

Nitrate ions (NO3) Sulfur in the form of sulfates (SO4^2-). Phosphorus as phosphates (PO4^3-). Magnesium ions (Mg2+)

Question 48

y does the plant need mineral salt, Nitrate ions (NO3)

Answer 48

provides nitrogen for the **synthesis of amino acids** from sugar molecules or smaller carbohydrate molecules. These **amino acids** are _joined_ together to form **proteins and enzymes**

Question 49

what happens to leaves when they are deficient in magnesium ions

Answer 49

Deficiency of magnesium ions results in the **yellowing** of leaves in a process called **chlorosis.**

Question 49

y does the plant need mineral salt, Sulfur

Answer 49

Sulfur is a component of some amino acids which form proteins

Question 50

y does the plant need mineral salt, phosphorus

Answer 50

Phosphorus is needed for DNA and for energy transfer reactions.

Question 51

y does the plant need mineral salt, magnesium

Answer 51

chlorophyll synthesis, which forms part of its structure.

Question 52

Transport of materials in plants occurs on three levels:

Answer 52

 the uptake of water and solutes by **individual cells,** such as the absorption of water and minerals from the soil by cells of a root  **short-distance transport** of substances from cell to cell at the level of tissues and organs involving **diffusion, osmosis and active transport**  **long-distance transport** of substances within **xylem and phloem** at the level of the whole plant. Materials are generally moved by mass flow, the bulk transport of materials from one point to another at the same speed as a result of pressure difference between the two points

Question 53

what happens when Deficiency of nitrate ions

Answer 53

Deficiency of nitrate ions leads to **poor growth** (poorly developed roots and shoots) due to the lack of nitrogen which is needed for the synthesis of amino acids that make up proteins for protoplasm build-up.

Question 54

xylem tissue purpose

Answer 54

Xylem tissue conducts **water and dissolved mineral salts** from the roots to the stems and leaves and provides **mechanical support** for the plant.

Question 55

what does the xylem consist of

Answer 55

trachied and vessel element

Question 55

xylem structure function, End walls of adjacent cells joined end to end are broken down, forming a continuous vessel

Answer 55

Allows water to flow in a **continuous column**

Question 56

xylem structure function, No living protoplasm / hollow tube

Answer 56

Reduces **resistance** to flow of water

Question 57

A sieve tube is made of narrow elongated sieve tube members joined end to end.

Answer 57

Allows continuous, longitudinal flow of organic substances

Question 57

xylem structure function, Narrow tube

Answer 57

To overcome downward force of gravity

Question 57

whats the tissue between the phloem and the xylem called

Answer 57

The phloem lies outside the xylem with a tissue called the **cambium** in between them. The cambium cells can **divide and differentiate** to form new xylem and phloem, giving rise to thickening of the stem.

Question 58

xylem structure function, Hollow lumen lined with cellulose

Answer 58

Effective adhesion of water molecules to wall of xylem vessel

Question 59

xylem structure function, Lignin deposited on inner side of xylem vessel wall

Answer 59

Prevents collapse under **large tension force** set up by **transpiration pull** and makes wall of xylem vessel **impermeable** to water so that water does not divert from its route

Question 60

In a dicotyledonous stem, where are the xylem and phloem

Answer 60

stem, xylem and phloem are grouped together to form vascular bundles. The vascular bundles are arranged in a ring round a central region called the **pith**. This pattern of arrangement helps the stem to **resist** the sideway bending forces caused by the *wind.**

Question 60

Adjacent cells separated by perforated end walls (sieve plates with pores)

Answer 60

Damaged sieve tubes may be sealed by plugging up sieve plate pores with P-protein (phloem protein) and callose (a carbohydrate), thus preventing further loss of sap

Question 60

A sieve tube member lacks a nucleus and most organelles and has a thin layer of cytoplasm

Answer 60

Allows a **smooth flow** of materials with little resistance

Question 61

Each sieve tube member is associated with one or more companion cells

Answer 61

Companion cells supply sieve tube members with **ATP molecules** and other substances

Question 62

what covers the stem (same as leaf)

Answer 62

The stem is covered by a layer of cells called the **epidermi**s. The **epidermal cells** are protected by **the cuticle** which **prevents evaporation of water **from the stem.

Question 62

whats the cortex and pith

Answer 62

the pith is the very centre, the vascular bundles surround it, the cortex surrounds the vascular bundles and is encapsuled by the epidermis

Question 63

function of cortex and pith

Answer 63

store up food substances (starch)

Question 63

In the dicotyledonous root, how are the phloems and xylem positioned

Answer 63

In the **dicotyledonous root**, the xylem and phloem are not bundled together. They lie on different radii, alternating with each other. (the cross in the centre is xylem and the outsides are phloem)

Question 63

Dicotyledonous stem vs Monocotyledonous stem vascular bundle placement

Answer 63

Dicot: Arranged in a ring Monocot: Scattered throughout the stem

Question 64

Dicotyledonous stem vs Monocotyledonous stem cambium presence?

Answer 64

dicot: yes monocot: no

Question 65

what is the root cap

Answer 65

The root cap **protects** the root tip from injury. It consists of undifferentiated cells.

Question 65

Dicotyledonous stem vs Monocotyledonous stem pith presence?

Answer 65

dicot: yes monocot: no

Question 65

where is the cortex for the dicot root

Answer 65

The cortex (the region between the epidermis and stele) of the root is a storage tissue.

Question 65

what is the stele

Answer 65

The **vascular tissue** of the root is found in the centre of the root in a region called the **stele**

Question 66

what is the piliferous layer

Answer 66

The **epidermis** of the root bearing root hairs is called the **piliferous layer**. The outer wall of these cells extends outwards to **form root hairs** _without_ any **cuticle.**

Question 66

What are companion cells

Answer 66

Each sieve tube member is associated with one or more companion cells Companion cells supply sieve tube members with **ATP molecules** and other substances

Question 66

dicot vs monocot root number of xylem tissue ridges

Answer 66

Dicot :Consists of three, four or five ridges of xylem tissue monocot: Consists of many (more than 5) ridges of xylem tissue

Question 66

dicot vs monocot root presence of pith?

Answer 66

dicot: absent monocot: Present at the centre of roots in most plants