AI-generated explanation. Check against your textbook.
Explanation:
Carrageenan is a gelatinous substance extracted from red algae (Rhodophyta). It is widely obtained from genera like Chondrus and Eucheuma. According to NCERT, carrageen is a product of red algae and is used as a thickening agent in foods. Green algae, brown algae, and blue-green algae do not produce carrageenan; brown algae produce algin, while agar is associated with some red algae as well.
🧠 Did You Know?
Red algae are known for their red pigments (phycobilins) and their cell walls contain carrageenan, which gives it its soothing, jelly-like texture in many foods.
💡 NCERT Memory Line:
Carrageenan is from red algae (Rhodophyta); algin from brown algae; agar is mainly from red algae as well.
Genera like Selaginella and Salvinia produce two
kinds of spores. Such plants are known as:
AI-generated explanation. Check against your textbook.
Explanation:
Plants like Selaginella and Salvinia produce two kinds of spores, i.e., microspores and megaspores. This condition is called heterospory. Therefore, the correct option is 4: Heterosporous.
Homosporous plants produce only one type of spore. Homosorus and Heterosorus are not standard terms used for spore types in NCERT; the correct biological term is heterospory for two spore sizes.
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In heterosporous plants, the two spores develop into male and female gametophytes, leading to seeds in many lineages.
💡 NCERT Memory Line:
Heterosporous plants produce two types of spores: microspores and megaspores.
AI-generated explanation. Check against your textbook.
Explanation:
Gemmae are asexual reproductive bodies found in some liverworts. They develop in structures called gemmae cups and help in rapid, clonal propagation. This aligns with NCERT's description of liverworts using gemmae for reproduction.
🧠 Did You Know?
Gemmae are a common feature of many liverworts, not mosses or Pteridophytes, and are not a typical feature of gymnosperms.
💡 NCERT Memory Line:
“Gemmae cups are present in some liverworts for asexual reproduction.”
AI-generated explanation. Check against your textbook.
Explanation:
Diadelphous stamens are two bundles of stamens usually seen in the Fabaceae family. In pea (Pisum sativum), the 10 stamens are arranged as 9 fused stamens forming a tube and 1 free stamen, i.e., they occur in two distinct groups. This arrangement is characteristic of many leguminous plants and is described in NCERT under floral morphology of dicot plants. Among the options, pea is the legume with diadelphous stamens, while China rose (Hibiscus) has many stamens united into a single column; citrus has numerous free stamens without two clear bundles. Thus, the correct choice is Pea (option 3).
🧠 Did You Know?
Diadelphous stamens form a specialized anther arrangement that aids pollen presentation in some legumes.
💡 NCERT Memory Line:
Diadelphous stamens are two bundles common in Fabaceae (peas), with 9 fused in one bundle and 1 free in the other.
AI-generated explanation. Check against your textbook.
Explanation:
Option 1 is incorrect. Mature sieve tube elements lack a nucleus and have very few cytoplasmic organelles; they rely on companion cells for metabolic needs. This is described in NCERT in the discussion of phloem tissue.
🧠 Did You Know?
Companion cells support sieve tube elements and help with loading/unloading of substances in phloem.
💡 NCERT Memory Line:
Mature sieve tube elements are enucleate and devoid of usual organelles; their metabolic functions are supported by companion cells.