Anatomy of Flowering Plants — BIOLOGY STD 11 Science — Question

While teaching cell division in the class, teacher told that during meiosis, the chromosome number is reduced to half of the parent, whereas during mitosis, the number remains the same. Seema was not able to recognise what teacher explained in the class and asked her elder brother, a botany student, the need of reducing chromosomes during gamete formation and what will happen if chromosome number will not reduced to its half. He explained the concept in detail to Seema.

1. In which part of the organisms does meiosis occur?
2. How does meiosis help in evolution?
3. Give the significance of meiosis.
4. What value is expressed in the behaviour of Seema's elder brother?

Angiosperms are the most advanced among plants and show more variety than any other division of plants. Additionally, most of the useful plants for us belong to the division angiosperm. Which of the following lessons can be taken from this? What are the benefits of learning multiple skills in our life?

1. A diverse group of students is always good for academic learning.
2. If a student knows multiple skills, then he is more likely to become relevant for the society.
3. A student with better physical features is likely to be a better student.

Ankita prepared hard for the test at home. All text based question and one practical based question on lock and key hypothesis was given to check whether the students had understood the phenomenon or not. Ankita who was a topper of class was the only student who was able to solve the problem. All others were unable to attempt the same. Teacher felt happy and asked Ankita to explain the process in the class.

1. Who proposed the lock and key hypothesis?
2. What is the nature of enzyme action?
3. Why are enzymes also called biocatalyst?
4. What values are reflected from Ankita's character?
5. The hypothesis was given by Emil Fischer in 1894.

The composition of glomerular filtrate and urine is not same. Comment.

Write any four differences between enzymes and co-enzymes.

Deciduous plants shed their leaves during hot summer or autumn. This process of shedding of leaves is called abscission. Apart from physiological changes, what anatomical mechanism is involved in the abscission of leaves?

Explain the following processes :
Polarisation of the membrane of a nerve fibre

Draw a labelled diagram of the ultrastructure of a cilium.

Explain the structure of thoracic chamber.

State the condition in which the flowers are described.

1. Perigynous.
2. Epigynous and.
3. Hypogynous.

Give one example of each plant in whih these flowers are found.