a. all plants
B. Fill in the blanks.
1. Living organisms that can not make their own food are called Heterotroph
2. In most plants glucose is converted into Proteins and stored in leaves, stems, roots etc.
3. Bacteria called
fixes nitrogen for leguminous plants.
4. The
carries water and minerals up the roots to the leaves, stem and branches.
5. The arrangement in which both types of plants mutually depend on each other is called
6.
obtain their nourishment by trapping and digesting insects and other animals.
following columns.
Answers
Explanation:
Plants obtain food in two different ways. Autotrophic plants can make their own food from inorganic raw materials, such as carbon dioxide and water, through photosynthesis in the presence of sunlight. Green plants are included in this group. Some plants, however, are heterotrophic: they are totally parasitic and lacking in chlorophyll. These plants, referred to as holo-parasitic plants, are unable to synthesize organic carbon and draw all of their nutrients from the host plant.
Plants may also enlist the help of microbial partners in nutrient acquisition. Particular species of bacteria and fungi have evolved along with certain plants to create a mutualistic symbiotic relationship with roots. This improves the nutrition of both the plant and the microbe. The formation of nodules in legume plants and mycorrhization can be considered among the nutritional adaptations of plants. However, these are not the only type of adaptations that we may find; many plants have other adaptations that allow them to thrive under specific conditions.
LEARNING OBJECTIVES
List the elements and compounds required for proper plant nutrition
Describe how symbiotic relationships help autotrophic plants obtain nutrients
Describe how heterotrophic plants obtain nutrients
Nutritional Requirements
Plants are unique organisms that can absorb nutrients and water through their root system, as well as carbon dioxide from the atmosphere. Soil quality and climate are the major determinants of plant distribution and growth. The combination of soil nutrients, water, and carbon dioxide, along with sunlight, allows plants to grow.
The Chemical Composition of Plants
Illustration shows a root tip. The tip of the root is bare, and hairs grow further up. A cross section at the top of the root reveals xylem tissue interspersed by four ovals containing phloem at the periphery.
Figure 1. Water is absorbed through the root hairs and moves up the xylem to the leaves.
Since plants require nutrients in the form of elements such as carbon and potassium, it is important to understand the chemical composition of plants. The majority of volume in a plant cell is water; it typically comprises 80 to 90 percent of the plant’s total weight. Soil is the water source for land plants, and can be an abundant source of water, even if it appears dry. Plant roots absorb water from the soil through root hairs and transport it up to the leaves through the xylem. As water vapor is lost from the leaves, the process of transpiration and the polarity of water molecules (which enables them to form hydrogen bonds) draws more water from the roots up through the plant to the leaves (Figure 1). Plants need water to support cell structure, for metabolic functions, to carry nutrients, and for photosynthesis.
Plant cells need essential substances, collectively called nutrients, to sustain life. Plant nutrients may be composed of either organic or inorganic compounds. An organic compound is a chemical compound that contains carbon, such as carbon dioxide obtained from the atmosphere. Carbon that was obtained from atmospheric CO2 composes the majority of the dry mass within most plants. An inorganic compound does not contain carbon and is not part of, or produced by, a living organism. Inorganic substances, which form the majority of the soil solution, are commonly called minerals: those required by plants include nitrogen (N) and potassium (K) for structure and regulation.
Essential Nutrients
Plants require only light, water and about 20 elements to support all their biochemical needs: these 20 elements are called essential nutrients (Table 1). For an element to be regarded as essential, three criteria are required: 1) a plant cannot complete its life cycle without the element; 2) no other element can perform the function of the element; and 3) the element is directly involved in plant nutrition.
Table 1. Essential Elements for Plant Growth
Macronutrients Micronutrients
Carbon (C) Iron (Fe)
Hydrogen (H) Manganese (Mn)
Oxygen (O) Boron (B)
Nitrogen (N) Molybdenum (Mo)
Phosphorus (P) Copper (Cu)
Potassium (K) Zinc (Zn)
Calcium (Ca) Chlorine (Cl)
Magnesium (Mg) Nickel (Ni)
Sulfur (S) Cobalt (Co)
Sodium (Na)
Silicon (Si)
Macronutrients and Micronutrients
The essential elements can be divided into two groups: macronutrients and micronutrients. Nutrients that plants require in larger amounts are called macronutrients. About half of the essential elements are considered macronutrients: carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium and sulfur. The first of these macronutrients, carbon (C), is required to form carbohydrates, proteins, nucleic acids, and many other compounds; it is therefore present in all macromolecules. On average, the dry weight (excluding water) of a cell is 50 percent carbon. As shown in Figure 2, carbon is a key part of plant biomolecules.