Try this, I am not sure if this will work in Access, as I am far more used to MSSQL2005 and above.
SUM(ISNULL([Physics],0)) AS Phy,
SUM(ISNULL([Chemistry],0)) AS Chem,
SUM(ISNULL([Physics],0)) + SUM (ISNULL([Chemistry],0)) AS Total
WHERE RTRIM(StudentID) = 'STUDENT1'
GROUP BY [Physics]
Just paste that into your SQL and then replace 'STUDENT1' with your '" & Trim(Me.txtSearch.Text) & "'" but.... I would be a bit concerned about using it as Dynamic SQL from the VB, as the user could enter SQL Injection to cause some trouble!
Try and use Stored Procedures with Parameters... As I am lead to believe this is safer....