Higher plants can be very well differentiated from animals but differentiation becomes difficult in between lower plants and lower animals. It is due to this reason that some organisms are classified as plants by botanists and as animals by zoologists e.g., Volvox, Euglena. However two groups can be differentiated on the basis of the following points:
11 Differences between plants and animals
1. Growth : In plants growth takes place by special type of cells present in the plant body in definite regions. Increase in length takes place by apical meristems present at the apices of shoots and roots and by intercalary meristems. Increase in girth (thickness), of the stem or root takes place by lateral meristems. In animals the growth takes place in all regions and not in specific regions as in plants. In addition growth in plants takes place upto just before their death, whereas in animals the growth ceases much before their death.
2. Cell wall : In plant cells the protoplasm is always enclosed by a cellulose (usually) wall, called cell wall. In animal cells there is no such wall.
3. Chlorophyll : In most of the plants a green pigment chlorophyll is present. In animals and some plants e.g., Fungi, chlorophyll is absent.
4. Photosynthesis : In the process of photosynthesis green organs of plants synthesize complex carbohydrates in the presence of sunlight, from CO2 and H2O taken up from the air and soil respectively. As chlorophyll is absent in animals they do not have the capacity to synthesize their food. Animals are dependent for their food on plants.
5. Movements : Most of the plants are fixed to the soil with the help of their roots or rhizoids. Their roots or branches however, show movements of curvature. But most of the animals move from one place to another (locomotion) in search of food and favorable environment. ‘This difference in movement of animals and plants is based upon the difference in the mode of nutrition.
6. Absorption of minerals : Plants absorb minerals from the soil in water soluble forms and utilize the same for their metabolism, whereas animals take their food in solid form.
7. Special excretory system : Animals have special excretory system to get rid of their waste products, whereas in plants excretion is done through removal of bark and fall of senescent leaves.
8. Centrosome (=Central body) : In animals a starshaped structure centrosome is present near the nucleus and this plays a significant role in cell division. This is absent in most of the plants. However this is found in some lower plants e.g., some Algae and Fungi.
9. Lysosome : A special type of body called lysosome containing large number of hydrolysing enzymes is present in animal cells only and in plant cells examples of their presence are few.
10. Vacuoles : A fully developed plant cell usually has a large central vacuole but it is not found in animal cell.
11. Cytokinesis : In animal cells, separation of daughter cells takes place by an equatorial constriction (i.e., periphery to centre) while in plant cells cytokinesis starts with the formation of phragmoplast which comprises the accumulation of interzonal microtubules and golgi vesicles first in the centre and then migrating towards the side walls (i.e., from centre to periphery). This structure is transformed into cell plate which separates the territories of the daughter cells, within cell plate the primary wall is produced later.