Plant Kingdom — BIOLOGY STD 11 Science — Question

While estimating the age of a tree, what will you observe on the transverse section of its trunk?

Metamorphosis of insects is regulated through hormone:

1. Pheromone.
2. Thyroxine.
3. Ecdysone.
4. All of these.

Why doesn't the enzyme pepsin digest the walls of the alimentary canal which are themselves made of protein? Write two reasons for this.

How does Cycas resemble bryophytes and pteridophytes?

Distinguish Cytokinesis from Karyokinesis.

Why are Deuteromycetes commonly known as imperfect fungi? Mention two characteristics of mycelium of such fungi.

Rahul's father bought an aquarium to home, while looking at the fishes, Rahul wondered that fishes, though small, can breathe efficiently in water. He wondered why do humans die of drowning. Next day, he asked his biology teacher about the same. The teacher explained that fishes have special respiratory organ, which allow them to breathe inside water. Rahul was amazed to know that even respiratory organs differ in different animal groups.

1. Give the name of the respiratory organ of fishes.
2. How do humans swim and breathe inside water?
3. Give the name of the respiratory organ of humans.
4. What values are displayed by Rahul?

Which one of the following statements is incorrect?

1. In cockroaches and prawns excretion of waste material occurs through malpighian tubules.
2. In ctenophores, locomotion is mediated by comb plates.
3. In Fasciola, flame cells help in excretion.
4. Earthworms are hermaphrodites and yet cross fertilization take place among them.

Different forms of the amino acids also has acidic amino acids. Write about it. Also, give structure of any one acidic amino acid.

What are essential and non-essential amino acids? Give four examples of each.