A wildlife officer studies regeneration in a freshwater planarian. Fig. 1 shows a planarian that was accidentally cut into three pieces during handling. Ove...
Question 1 Report
A wildlife officer studies regeneration in a freshwater planarian. Fig. 1 shows a planarian that was accidentally cut into three pieces during handling. Over several days, cells close to each cut edge divide. The front piece grows a new tail, the middle piece grows a head and tail, and the rear piece grows a head. The officer returns all animals to clean water after the observation.
(a) Identify the process used to make the new cells at each cut edge. [1]
(b) Describe what happens to cell number during this process. [1]
(c) Explain why the new cells need to differentiate after mitosis. [2]
(d) Use Fig. 1 to identify which piece must form both a head and a tail. [1]
(e) Suggest one reason why the officer should return the animals to the same island stream where they were collected. [1]
Answer Details
(a) Mitosis [1] (b) One cell divides to form two cells / cell number increases [1] (c) Different specialised cells are needed [1]; to form different tissues and structures such as head, tail or muscles [1] (d) The middle piece [1] (e) It is their natural habitat / returning them limits disturbance to a different population or species [1]
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