Error using Oracle Ref Cursor

I'm trying to do something fairly simple, I am trying to automate the removal and back up of tables from my personal table space. I have about 100 tables and want to get rid of all of them (except a table that I'm using to store the table names), but want to keep the data from the tables in case I need them sometime in the future. Below is the code I am trying to use to accomplish this. I am getting an error on the ref cursor, which I'll include below my code. I half expect somebody to tell me I'm an idiot and explain an easier way to do this. If not, please tell me what I'm doing wrong with the way that I am doing it, thanks.

DECLARE
    v_folder_name        VARCHAR2(100) := 'MY_FOLDER';
    TYPE QRY_CURSOR      IS REF CURSOR;
    v_qry_cursor         QRY_CURSOR;
    v_file_name          VARCHAR2(320);
    v_file               sys.utl_file.file_type;
    v_max_buffer_length  CONSTANT BINARY_INTEGER := 32767;
    v_qry_str            VARCHAR2(4000); --I've tried this with 32767, made no difference
    v_drop_string        VARCHAR2(4000);
    v_dynamic_record     VARCHAR2(4000); --tried this with 32767 also

CURSOR GET_TABLE_NAMES IS
    SELECT * FROM TEMP_BACKUP_TABLE WHERE TABLE_NAME <> 'TEMP_BACKUP_TABLE';

FUNCTION startFile(file_name VARCHAR2)
    --working function, used with many procedures, left out for brevity
END startFile;

FUNCTION closeFile(file_name VARCHAR2)
    --working function, used with many procedures, left out for brevity
END closeFile;

BEGIN
    INSERT INTO TEMP_BACKUP_TABLE SELECT DISTINCT TABLE_NAME FROM ALL_TAB_COLS WHERE OWNER = 'ME';
    COMMIT;
FOR REC IN GET_TABLE_NAMES LOOP
    v_file_name := REC.TABLE_NAME;
    v_file := startFile(v_file_name);
    v_qry_str := 'SELECT * FROM ' || v_file_name;
    v_drop_string := 'DROP TABLE ' || v_file_name;
    OPEN v_qry_cursor FOR v_qry_str;  -- this is the line that returns an error
    LOOP
        FETCH v_qry_cursor INTO v_dynamic_record;
        EXIT WHEN v_qry_cursor%NOTFOUND;
        sys.utl_file.put_line(v_file, v_dynamic_record);
    END LOOP;

    CLOSE v_qry_cursor;
    EXECUTE IMMEDIATE v_drop_string;
    COMMIT;

    v_file := closeFile(v_file_name);
END LOOP;
DELETE FROM TEMP_BACKUP_TABLE;
END;

The error I'm getting is as follows:

Error report:
ORA-00932: inconsistent datatypes: expected - got -
ORA-06512: at line 73
00932. 00000 - "inconsistent datatypes: expected %s got %s"
*cause:
*action:

Thanks for any help.