Trying to make a group of fields required on combobox selection in Access 2010 - ms-access-2010

Question

In Access 2010.
I have 3 separate groups of fields that can be active based on a combobox selection but I'm trying to get them to be required as well. I've looked everywhere but it doesn't appear to be any VB code to make a field required. Is there anyway I can accomplish this?
The code I have right now to make the selected group of fields active and make the one's not selected blank:
Private Sub Combo109_Click()
If Combo109 = "Germ" Then
cg_moisture.Enabled = True
cg_oil_nir.Enabled = True
extraneous_material.Enabled = True
fines.Enabled = True
cg_moisture.Enabled = True
cg_oil_nir.Enabled = True
extraneous_material.Enabled = True
fines.Enabled = True
Moist_cgm_nir.Enabled = False
prot_cgm_nir.Enabled = False
oil_cgm_nir.Enabled = False
meal_color.Enabled = False
load_out_temp.Enabled = False
moist_cgf_nir.Enabled = False
prot_cgf_nir.Enabled = False
oil_cgf_nir.Enabled = False
profat_nir.Enabled = False
starch_nir.Enabled = False
total_sug_nir.Enabled = False
loadout_temp.Enabled = False
screen_thrus.Enabled = False
screen_thrus.Value = ""
Moist_cgm_nir.Value = ""
prot_cgm_nir.Value = ""
oil_cgm_nir.Value = ""
meal_color.Value = ""
load_out_temp.Value = ""
moist_cgf_nir.Value = ""
prot_cgf_nir.Value = ""
oil_cgf_nir.Value = ""
profat_nir.Value = ""
starch_nir.Value = ""
total_sug_nir.Value = ""
loadout_temp.Value = ""
screen_thrus.Value = ""
screen_thrus.Value = ""
End If

Answer 1

IF all of the controls are in the 'Detail' section of your form, AND if a contrtol is Enabled, you require a value, then the code below should work. If you want more meaningful names to be displayed, either change your control names, or place a better name in the control 'Tag' field and reference that. The following code only checks Textboxes and CheckBoxes - modify to suit your needs.
Private Sub Form_BeforeUpdate(Cancel As Integer)
Dim ctl As Control
Dim blnMissing As Boolean
Dim strMissing As String
For Each ctl In Me.Section("Detail").Controls
If ctl.ControlType = acTextBox Or ctl.ControlType = acCheckBox Then
If ctl.Enabled = True Then
'Debug.Print ctl.Name & vbTab & ctl.Value
If ctl.Properties("Enabled") = True Then
If Me(ctl.Name) = "" Or IsNull(Me(ctl.Name)) Then
blnMissing = True
strMissing = strMissing & ctl.Name & "; "
End If
End If
End If
End If
Next ctl
If blnMissing = True Then
MsgBox "You are required to enter data in fields: " & strMissing, vbOKOnly + vbCritical, "Missing Required Data"
Cancel = True
End If
End Sub