This set of Biology Multiple Choice Questions & Answers (MCQs) focuses on “Growth and Development in Plants – 1”.
1. All the cells of the plant are descendants of which of the following?
a) Apical tissue
b) Intercalary tissue
Explanation: All cells of a plant are descendants of the zygote. Trees continue to increase in height or girth over some time. However, the leaves, flowers and fruits of the same tree appear and fall periodically and sometimes repeatedly.
2. Development is the sum of how many processes?
Explanation: Development is the sum of two processes-growth and differentiation. To begin with, it is essential and sufficient to know that the development of a mature plant from a zygote follows a precise and highly ordered succession of events.
3. What is the first step in the process of plant growth?
a) Seed fermentation
b) Seed desiccation
c) Seed germination
d) Seed dormancy
Explanation: The first step in the process of plant growth is seed germination. The seed germinates when favourable conditions are available like the presence of oxygen, water and certain enzymes. If these conditions are not available, then a seed may suspend its activities and will germinate only when these conditions become available.
4. Which of the following is the most fundamental characteristic of a living being?
Explanation: Growth is regarded as one of the most fundamental and conspicuous characteristics of a living being. Growth can be defined as an irreversible permanent increase in the size of an organ or its part or even of an individual cell.
5. Growth occurs by only anabolic processes.
Explanation: Growth is accompanied by metabolic processes which include both anabolic and catabolic processes, that occur at the expense of energy. Therefore, for example, expansion of a leaf is growth.
6. Unlimited growth of the plant, is due to the presence of which of the following?
c) Apical cells
d) Special organs
Explanation: Unlimited growth of the plants is due to the presence of meristems which are actively dividing cells and are present at the tips of root and shoot. The cells of these meristems are small and have dense protoplasm. They also have a high nucleo-cytoplasmic ratio.
7. Which of the following kinds of growth is exhibited by plants?
a) Closed-form of growth
b) The open form of growth
c) Both open and closed form of growth
d) Fused form of growth
Explanation: Open form of growth is exhibited by the plants as at the tips of root and shoot, continuously dividing cells of meristems are present which are ultimately responsible for their unlimited growth. Viruses cannot multiply in these continuously dividing cells.
8. Which of the following meristem is responsible for the primary growth of the plant?
a) Apical meristem
b) Lateral meristem
c) Vascular cambium
d) Cork cambium
Explanation: Root apical meristem and shoot apical meristem are responsible for the primary growth of the plants and principally contribute to the elongation of the plants along their axis.
9. Which of the following meristem is not responsible for the secondary growth of plants?
a) Lateral meristem
b) Vascular cambium
c) Apical meristem
d) Cork cambium
Explanation: In dicotyledonous plants and gymnosperms, the lateral meristems, vascular cambium and cork cambium appear later in life. These are the meristems that cause an increase in the girth of the organs in which they are active. This is known as secondary growth of the plant.
10. Growth is a consequence of which of the following?
a) Increase in the amount of protoplasm
b) Increase in the amount of DNA
c) Increase in the amount of cytoplasm
d) Increase in the amount of RNA
Explanation: Growth at a cellular level is principally a consequence of the increase in the amount of protoplasm. Since an increase in protoplasm is difficult to measure directly, one generally measures some quantity which is more or less proportional to it.
11. One single maize root apical meristem can give rise to how many new cells per hour?
Explanation: One single root apical meristem can give rise to more than 17,500 new cells per hour, whereas cells in watermelon may increase in size by up to 3,50,000 times. In the former, growth is expressed as an increase in cell number and the latter expresses growth as an increase in the size of the cell.
12. Growth of a pollen tube is measured in terms of its surface area.
Explanation: The growth of a pollen tube is measured in terms of its length, an increase in surface area denotes the growth in a dorsiventral leaf. Growth is, therefore, measured by a variety of parameters.
13. In how many phases the period of growth is divided?
Explanation: The period of growth is generally divided into three phases, namely, meristematic, elongation and maturation. Growth is measured by a variety of parameters like increase in fresh weight, dry weight, length, area, volume and cell number.
14. The root and shoot apex of a plant represent which phase of the growth?
Explanation: The constantly dividing cells, both at the root apex and the shoot apex, represent the meristematic phase of growth. The cells in this region are rich in protoplasm and possess large conspicuous nuclei.
15. Which of the following is not a characteristic of the cell walls of root apex meristem?
a) Secondary in nature
d) Abundant plasmodesmatal connections
Explanation: The cell walls of root and shoot apex meristem are primary, thin and cellulosic with abundant plasmodesmatal connections. The cells proximal to the meristematic zone represent the phase of elongation.
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