1. Which country has recently experienced a massive outbreak of the toxic algae Karenia mikimotoi?
[A] Japan
[B] Indonesia
[C] Australia
[D] Malaysia
Show Answer
Correct Answer: C [Australia]
Notes:
A massive toxic algal bloom of Karenia mikimotoi off South Australia, first detected in March 2025, has killed over 400 marine species and hit tourism and fishing hard. The bloom spans 4,500 square km and is worsened by a marine heatwave since 2024 with 2.5°C rise in sea temperature. Karenia mikimotoi is a red-tide dinoflagellate commonly found in the eastern North Atlantic and around Japan. It releases hemolytic and ichthyo toxins that cause mass deaths of fish, shellfish, crustaceans, and echinoderms. Though it does not directly harm humans, its blooms create anoxic (oxygen-depleted) waters when dead cells decay.
2. Consider the following potential ecological concerns associated with the SeaCURE project’s method of carbon extraction from seawater:
- Release of CO₂ back into the atmosphere, worsening climate change
- Acidification of seawater that could negatively impact marine life, especially organisms that rely on carbon for their biological processes
- Reduction in the ocean’s capacity to absorb CO₂, worsening ocean acidification
- Potential generation of harmful algae blooms that affect marine ecosystems
Which of the above statements is / are correct?
[A] Only 2
[B] 3 and 4 only
[C] 1 and 2 only
[D] 2 and 4 only
Show Answer
Correct Answer: A [Only 2]
Notes:
The correct answer is option 1, “Only 2”, since the acidification process might negatively impact marine organisms, particularly those reliant on carbon. The other options, namely 1, 3, and 4 are incorrect as the SeaCURE project aims to capture, not release CO₂ into the atmosphere, and does not reduce the ocean’s ability to absorb CO₂ or generate harmful algae blooms.
3. With reference to “The Status of Coral Reefs of the World 2020” report, consider the following statements:
- According to the report, 14% of the world’s corals were wiped out by coral bleaching events between 2009 and 2018.
- According to the report, the proportion of algae in the corals has increased since 2010.
- According to the report, all areas experienced a decline in coral cover.
Which of the above given statements is/are correct?
[A] Only 1 & 2
[B] Only 2 & 3
[C] Only 1 & 3
[D] 1, 2 & 3
Show Answer
Correct Answer: A [Only 1 & 2]
Notes:
The Status of Coral Reefs of the World 2020 report by the Global Coral Reef Monitoring Network and the Australian government reveals that 14% of global corals were lost to bleaching from 2009 to 2018, primarily due to rising sea surface temperatures. Since 2010, algae in corals have increased, correlating with a decline in hard corals. However, coral cover in East Asia, home to 30% of the world’s reefs, has increased.
4. Which of the following statements on types of aquacultures is/are correct?
- Cage culture – allows water to pass freely.
- Algaculture – farming of algae.
- Fish farming – can be done only in seawater.
- Mariculture – can be done in any freshwater.
Choose the correct answer using the codes given below:
[A] Only 1 & 2
[B] Only 2 & 3
[C] Only 2, 3 & 4
[D] 1, 2, 3 & 4
Show Answer
Correct Answer: A [Only 1 & 2]
Notes:
Cage culture allows water to pass freely, involving the confinement of aquatic organisms in submerged cages. Algaculture refers to the farming of algae for food, feed, biofuel, or environmental uses in controlled environments. Fish farming, or aquaculture, can occur in freshwater, brackish, or seawater, while mariculture specifically involves marine organisms in saltwater, not freshwater. The correct statements are: Cage culture allows water to pass freely. Algaculture is the farming of algae.
5. Algae belongs to which of the following levels of the ecosystem?
[A] Decomposers
[B] Destructors
[C] Producers
[D] Consumers
Show Answer
Correct Answer: C [Producers]
Notes:
Most types of algae are classified as producers within an ecosystem because they are able to produce their own food. However, while most algae are autotrophs, meaning they can produce their own food through inorganic compounds, there are a minority of algae types that are heterotrophs (e.g. euglenophyte), meaningthat they cannot make their own food.
6. Which of the following is/are correct for fungi?
- These are heterotrophic eukaryotic organisms.
- Their mode of nutrition can be autotrophic or heterotrophic.
- Some fungal species live in permanent mutually dependent relationships with bluegreen algae.
Select the correct answer from the codes given below:
[A] Only 1 and 2
[B] Only 2 and 3
[C] Only 1 and 3
[D] All of the above
Show Answer
Correct Answer: C [Only 1 and 3]
Notes:
These are heterotrophic eukaryotic organisms. Some of them use decaying organic material as food and are therefore called saprotrophs. Others require a living protoplasm of a host organism for food. They are called parasites. Many of them have the capacity to become multicellular organisms at certain stages in their life. Some fungal species live in permanent mutually dependent relationships with bluegreen algae (or cyanobacteria). Such relationships are called symbiotic. These symbiotic life forms are called lichens.
7. Which of the following is/are correct for Monera?
- These organisms do not have a defined nucleus or organelles.
- The mode of nutrition of organisms in this group can be either by synthesising their own food (autotrophic) or getting it from the environment (heterotrophic).
- Examples are unicellular algae, diatoms and protozoans.
Select the correct answer from the codes given below:
[A] Only 1 and 2
[B] Only 2 and 3
[C] Only 1 and 3
[D] All of the above
Show Answer
Correct Answer: A [Only 1 and 2]
Notes:
These organisms do not have a defined nucleus or organelles, nor do any of them show multi-cellular body designs. On the other hand, they show diversity based on many other characteristics. Some of them have cell walls while some do not. Of course, having or not having a cell wall has very different effects on body design here from having or not having a cell wall in multicellular organisms. The mode of nutrition of organisms in this group can be either by synthesising their own food (autotrophic) or getting it from the environment (heterotrophic). This group includes bacteria, blue-green algae or cyanobacteria, and mycoplasma.
8. Which of the following is/are correct for Protista?
- This group includes many kinds of unicellular prokaryotic organisms.
- Their mode of nutrition can be autotrophic or heterotrophic.
- Examples are unicellular algae, diatoms and protozoans.
Select the correct answer from the codes given below:
[A] Only 1 and 2
[B] Only 2 and 3
[C] Only 1 and 3
[D] All of the above
Show Answer
Correct Answer: B [Only 2 and 3]
Notes:
This group includes many kinds of unicellular eukaryotic organisms. Some of these organisms use appendages, such as hair-like cilia or whip-like flagella for moving around. Their mode of nutrition can be autotrophic or heterotrophic. Examples are unicellular algae, diatoms and protozoans.
9. Which of the following is/are correct for Thallophyta?
- Plants do not have well-differentiated body design.
- They are also called algae.
- Examples are Spirogyra, Ulothrix,
Select the correct answer from the codes given below:
[A] Only 1 and 2
[B] Only 2 and 3
[C] Only 1 and 3
[D] All of the above
Show Answer
Correct Answer: D [All of the above ]
Notes:
Plants that do not have well-differentiated body design fall in this group. The plants in this group are commonly called algae. These plants are predominantly aquatic. Examples are Spirogyra, Ulothrix, Cladophora, Ulva and Chara.
10. Which of the following is/are true for eukaryotic cells?
- The cells having nuclear material without nuclear membrane.
- Examples are bacteria and blue green algae.
Select the correct answer from the codes given below:
[A] Only 1
[B] Only 2
[C] Both 1 and 2
[D] None of the above
Show Answer
Correct Answer: D [None of the above ]
Notes:
The nucleus of the bacterial cell is not well-organised like the cells of multicellular organisms. There is no nuclear membrane. The cells having nuclear material without nuclear membrane are termed prokaryotic cells. The organisms with these kinds of cells are called prokaryotes (pro : primitive; karyon : nucleus). Examples are bacteria and blue green algae. The cells, like onion cells and cheek cells having well-organised nucleus with a nuclear membrane are designated as eukaryotic cells. All organisms other than bacteria and blue green algae are called eukaryotes. (eu : true; karyon: nucleus).
