Test: Algae - NEET MCQ

Thalloids have thallus(body) is not differentiated into leaves, or stem, etc. They do not have a vascular bundles also.

Let's analyze each pair to identify the incorrectly matched one:

1. Chlamydomonas: Microscopic unicellular algae

   • This is correct. Chlamydomonas is indeed a microscopic unicellular alga.

2. Volvox: Colonial algae

   • This is correct. Volvox forms colonial structures, making it a colonial alga.

3. Ulothrix: Filamentous algae

   • This is correct. Ulothrix is a filamentous green alga.

4. Fucus: Isogamous algae

   • This is incorrect. Fucus is a type of brown alga that reproduces via oogamous reproduction, not isogamous. Isogamous algae have gametes of similar shape and size, whereas Fucus has distinct male and female gametes.

So the incorrectly matched pair is:

4 Fucus: Isogamous algae

In chlorophyceae, chloroplasts contain storage bodies called Pyrenoids. Pyrenoids consists of proteins and starch. Chlorophyceae sometimes store food as oil droplets.
Hence the correct option is "A" 

• Autotrophs: The term "Autotrophs" refer to organisms, that can produce their own food from the inorganic substances found in the surroundings.
• Algae: Algae which are predominantly aquatic organisms carry out photosynthesis to prepare their food.
• These fresh water, brackish and marine water inhabitants with no differentiation of stem, roots and leaves make use of the chlorophyll and other photosynthetic pigments present in their thallus for photosynthesis.

Hence, the correct answer is Option C

The given diagram if of Brown Algae ( Fucus)

et’s examine each statement about brown algae Fucus to determine which one is incorrect:

1. Contains laminarin or mannitol as reserve food.

   • This is correct. Brown algae like Fucus store reserve food in the form of laminarin and mannitol.

2. They possess chlorophyll a, c, carotenoids and xanthophylls.
   This is correct phaeophyceace possess all these pigments.

3. Union of gametes may take place in water or within the oogonium.

   • This is correct. In Fucus, fertilization can occur either in the water or within the oogonium (the female reproductive structure).

4. Gametes with two apically inserted flagella.

   • This is incorrect. In Fucus, the gametes (sperm) have two laterally inserted flagella, not apically inserted.

So, the incorrect statement about Fucus is:

4. Gametes with two apically inserted flagella.

Option B is incorrect 

Chlorophyll a and b is found in green algae.

Correct option is D. Chlorella

The algae reproduce by vegetative, asexual and sexual methods. Vegetative reproduction is by fragmentation. Each fragment develops into a thallus. Asexual reproduction is by the production of different types of spores, the most common being the zoospores.

1. Chlorophyceae:

• Pigment: Chlorophyll a, b
• Stored food: Starch
• Flagella: 2-8 equal

2. Phaeophyceae (not Pheophyceae):

• Pigment: Chlorophyll a, c, Fucoxanthin
• Stored food: Laminarin
• Flagella: 2, lateral unequal

3. Rhodophyceae:

• Pigment: Chlorophyll a, d, Phycoerythrin
• Stored food: Floridean starch
• Flagella: Absent

Based on these points:

1. a (Stored food for Chlorophyceae) is Starch.
2. b (Class for the given pigments and stored food) is Phaeophyceae.
3. c (Flagella for Phaeophyceae) is 2, lateral unequal.
4. d (Stored food for Rhodophyceae) is Floridean starch.

So, the correct option is:

4. a : Starch; b : Phaeophyceae; c : 2 lateral unequal; d : Floridean starch

Algae are useful to man in a variety of ways. At least a half of the total carbon dioxide fixation on earth is carried out by algae through photosynthesis. Being photosynthetic they increase the level of dissolved oxygen in their immediate environment. They are of paramount importance as primary producers of energy-rich compounds which form the basis of the food cycles of all aquatic animals

 Certain marine brown and red algae produce large amounts of hydrocolloids (water holding substances), e.g., algin (brown algae) and carrageen (red algae) which are used commercially. Brown:- Phaeophyceae, red:- Rhodophyceae

Correct answer: C. Laminaria (brown algae)

Explanation:
Laminaria, a type of brown algae, has a body structure divided into three parts: the holdfast (which anchors the algae to the substrate), the stipe (a stem-like structure), and the frond (the leaf-like structure).

The members of phaeophyceae or brown algae are found primarily in marine habitats. They show great variation in size and form. They range from simple branched, filamentous forms (Ectocarpus) to profusely branched forms as represented by kelps, which may reach a height of 100 metres.They possess chlorophyll a, c, carotenoids and xanthophylls. They vary in colour from olive green to various shades of brown depending upon the amount of the xanthophyll pigment, fucoxanthin present in them. Food is stored as complex carbohydrates, which may be in the form of laminarin or mannitol. The vegetative cells have a cellulosic wall usually covered on the outside by a gelatinous coating of algin. The protoplast contains, in addition to plastids, a centrally located vacuole and nucleus. The plant body is usually attached to the substratum by a holdfast, and has a stalk, the stipe and leaf like photosynthetic organ – the frond.

Correct answer: B. 6

Explanation:

The correct statements are:

I. True. Brown algae contain chlorophyll a, c, and fucoxanthin, which give them their characteristic color.
II. True. Laminarin and mannitol are the storage products in brown algae.
III. True. The cell wall of brown algae is composed of cellulose and is covered with algin, a gelatinous substance.
IV. False. Brown algae have a centrally located vacuole and nucleus.(correction of false statement.
V. True. The photosynthetic organs of brown algae are called fronds, which are leaf-like structures.
VI. True. Brown algae produce pear-shaped biflagellate zoospores.
VII. True. The zoospores have two unequal, laterally attached flagella.

So, the number of correct statements is 6.

Certain marine brown and red algae produce large amounts of hydrocolloids (water holding substances), e.g., algin (brown algae) and carrageen (red algae) which are used commercially. Agar, one of the commercial products obtained from Gelidium and Gracilaria are used to grow microbes and in preparations of ice-creams and jellies. Chlorella a unicellular alga rich in proteins is used as food supplement even by space travellers

The primary pigment responsible for the red color in most red algae is R-phycoerythrin. This pigment gives the red algae their characteristic color. Red algae are commonly found in marine habitats, and R-phycoerythrin is the dominant pigment in their bodies.

Most of the members of green algae have one or more storage bodies called pyrenoids located in the chloroplasts. Pyrenoids contain protein besides starch. Some algae may store food in the form of oil droplets.

Sexual reproduction is the process of the fusion of two gametes. The gametes that undergo fusion can be flagellated and similar in size (as in Ulothrix) or non-flagellated (non-motile) but similar in size (as in Spirogyra). This type of reproduction is called isogamous.

According to the NCERT reference, kelps are large, brown seaweeds found in marine environments. They are classified as marine algae, specifically within the group of brown algae.

The form and size of algae is highly variable, ranging from colonial forms like Volvox.

Chlorophyll a only  is the common pigment in each algae.

Fusion between one large, non motile (static) female gamete and a smaller, motile male gamete is termed oogamous, e.g., Volvox, Fucus.

Sexual reproduction takes place through fusion of two gametes. These gametes can be flagellated and similar in size (as in Ulothrix) or non-flagellated (non-motile) but similar in size (as in Spirogyra). Such reproduction is called isogamous

Fusion of two gametes dissimilar in size, as in species of Eudorina is termed as anisogamous. Fusion between one large, nonmotile (static) female gamete and a smaller, motile male gamete is termed oogamous, e.g., Volvox, Fucus.