Chapter 29, Problem 1TY

Summary Introduction

Introduction: The modern plants are the descendants of the small and simple plants which could survive on land. The modern land plants do not require water to complete their life cycle, but their ancestors could not complete their life cycle without water.

Answer to Problem 1TY

Correct answer: The liverworts are probably the simplest and most ancient phylum of the modern land plants. Hence, the correct answer is option c.

Explanation of Solution

Reason for correct answer:

Liverworts belong to the phylum bryophyte and these organisms have a simple morphology. Their body is composed of thallus, stalk, and rootlets. They require water to complete their life cycle and have gametophyte as the dominant stage of the life cycle. Hence, the liverworts are the simplest and most ancient phylum of modern plants.

Option c. is given as “the liverworts”.

The modern plants have simplest and most ancient phylum probably as the liverworts. Hence, the correct answer is option c.

Reasons for the incorrect answer:

Option a. is given as, “the pteridophytes”.

The pteridophytes are the vascular plants and have complex morphology compared to the liverworts. Hence, option a. is incorrect.

Option b. is given as, “the cycads”.

The cycads belong to the gymnosperm group. They have a dominant sporophytic stage in their life cycle and have complex stele just like modern land plants. Hence, option b. is incorrect.

Option d. is given as, “the angiosperms”.

The modern land plants are themselves classified into angiosperms. Therefore angiosperms are not the simplest and most ancient phylum of modern-day plants. Hence, option d. is incorrect.

Option e. is given as, “none of the above”.

The liverworts are probably the simplest and most ancient phylum of the modern day plants. Hence, option e. is incorrect.

Hence, the options a., b., d., and e. are incorrect.

Conclusion

The simplest and most ancient phylum of modern land plants is probably the liverworts.