A sigmoid growth curve is characteristic of –

• (a) Bacteria growing in culture medium

• (b) Organisms growing in natural habitat

• (c) All cells, tissue and organs

• (d) All

Which of the following is cytokinin?

• Phytochrome

• LeucineEthylene

• ethylene

• Zeatin

Apical meristems can be found in

• The leaves

• The tips of the shoots and roots

• The xylem cells

• The epidermal cells

Hormone responsible for plant ans seed dormancy during draught is

• IBA

• NAA

• ABA

• Zeatin

1.)    Which of the following differentiates between the terms growth and development?

• Growth is increase in complexity and development is increase in size.

• Development and growth are the same.

• Growth is increase in size and development is increase in complexity.

• Development does not involve growth.

Fruit and leaf drop at early stages can be prevented by the application of:

• Ethylene

• Auxins

• Gibberellic acid

• Cytokinins

The impulses from CNS to skeletal muscles are relayed through

• SNS

• Somatic neural system

• PSNS

• All of these

Removal of shoot tips is a very useful technique to boost the production of tealeaves. This is because :

• Gibberellins delay senescence of leaves.

• Gibberellins prevent bolting and are inactivated.

• Auxins prevent leaf drop at early stages.

• Effect of auxins is removed and growth of lateral buds is enhanced.

Which of the following includes all three process –

• (a) Differentiation

• (b) Cell enlargement

• (c) Seed germination, senescence

• (d) Development

Seed dormancy can be broken by :

• ABA and GA₃

• GA₃ and ethylene

• IAA and ABA

• ABA and IPA