Category: Biology Second Paper Lecture Sheet

(i) Greenish-grey spots are seen on the tips and edges of the leaves. The spots are round or uneven in shape.
(ii) The spots are large, light brown in color and eventually turn reddish black or blackish brown.
(iii) Rotting occurs with dark wet spots on the leaves.
(iv) A velvety coating is formed on the affected area.
(v) Root mycelium and conidiophores are seen on the underside of leaves.
(vi) Spots spread to petioles or petioles.
(vii) Diseased leaves become scorched.
(viii) Dry rot in tubers.

1. Leaf disease symptoms
(i) Greenish-grey spots are seen on the tips and edges of the leaves. The spots are round or uneven in shape.
(ii) The spots are large, light brown in color and eventually turn reddish black or blackish brown.
(iii) Rotting occurs with dark wet spots on the leaves.
(iv) A velvety coating is formed on the affected area.
(v) Root mycelium and conidiophores are seen on the underside of leaves.
(vi) Spots spread to petioles or petioles.
(vii) Diseased leaves become scorched.
(viii) Dry rot in tubers.
2. Stem disease symptoms
(i) In cloudy and humid weather the spots spread from leaves to stems and the plant droops.
(ii) At 12-250 C, the spots spread throughout the plant body.
(iii) If the attack is severe, the infected plant gives off a bad smell like rotten eggs.
(iv) Diseased plants die and turn black.
3. Disease symptoms in potato
(i) Reddish-brown spots appear on diseased potatoes or tubers.
(ii) Reddish brown black spots are seen on the skin of diseased potato.
(iii) Tuber moist rot.
(iv) Dry rot in tubers.
(v) Potato or tuber yield is reduced.

1. The mycelium of the fungus is like a colorless white cotton.
2 Fungal mycelium is highly branched and sinocytic.
3. They live as dead animals or parasites.
4. It resides in the intercellular spaces of the host and absorbs food by haustoria.
5. Branches of sporangiophores produce lemon-shaped sporangium.
6. Sporangium produces bi-flagellated spores.
7. A single conidium is produced at the apex of each branch of the conidiophore.
8. Conidia are ovoid, thick-walled, with granular protoplasm and multiple nuclei.
9. It is a diploid fungus. Its cells have 11-13 chromosomes. It contains 240 million base pairs and 18000 genes.

Primary transmission of the disease occurs from infected potatoes. Dormant mycelium becomes active on seedlings from diseased potatoes. Conidiophores are produced from the mycelium of the fungus. Conidia are produced in conidiophores. Conidia spread with water and wind and invade new plants.
Outbreaks of this disease are seen in Asia, North America, Europe, Caribbean Islands, Oceania, Australia, Fiji, New Caledonia, New Zealand and Papua New Guinea. If the temperature is very low in winter, there is a possibility of this disease in Bangladesh.

Potato late blight is caused by the fungus Phytophthora infestans. (But early blight of potato is caused by the fungus Alternaria solani)

100 grams of mushrooms are nutritious
1. Sugars ——————– 4.3 grams
2. Protein —————— 2.5 grams
3. vitamins
(i) Niacin —————– 3.8 mg
(ii) Pantothenic acid – 1.5 mg
(iii) Riboflavin ———- 0.5 mg
(iv) Thiamine ————— 0.1 mg
(v) Vitamin C ———— Little
4. Fat ——————- 0.1 g
5. Mineral salts
(i) Potassium ————- 448 mg
(ii) Phosphorus ———– 120 mg
(iii) Calcium ———- 18 mg
(iv) Sodium ———— 6 mg
(v) Zinc —————– 1.1 mg

1. Poisonous species are brightly colored.
2. They are acidic and pungent.
3. Poisonous species do not grow in the sun.
4. Basidiospores of poisonous species are purple in color.
5. Most species grow on wood.

1. Toxicity: Eating poisonous species of mushrooms can cause death to humans and other animals. Agaricus xanthodermus is a poisonous species. The most poisonous species are Amanita virosa and Amanita phalloides.
2. Depletion of soil organic matter: Mushrooms absorb organic matter from the soil. As a result, habitat soil organic matter decreases.
3. Destructive action: Mushrooms cause damage to wood, straw, bamboo, furniture etc.

Mushroom cultivation is a labor intensive cottage industry. The men and women of the family are cultivating mushrooms together. Family poverty is eliminated. Many mushroom industries have developed in Savar and Manikganj.

Agaricus is used to remove industrial waste, oil and pesticides from the environment.