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                                                                Exhibit 10(k)




                              CN BIOSCIENCES, INC.
               SECOND AMENDED AND RESTATED 1992 STOCK OPTION PLAN

                                   *   *   *

                                   ARTICLE I

                                    Purpose

                 The CN Biosciences, Inc. Second Amended and Restated 1992
Stock Option Plan (the "Plan") is intended as an incentive to improve the
performance, encourage the continued employment, and increase the proprietary
interest of certain directors, officers, key employees and consultants of CN
Biosciences, Inc. (the "Company") and its subsidiaries who shall participate in
the Plan.  The Plan is designed to grant such directors, officers, key
employees and consultants the opportunity to share in the Company's long-term
success through stock ownership and to afford them the opportunity for
additional compensation related to the value of the Company's stock.

                 The word "Employer", when used in the Plan, shall include the
Company or one of its subsidiaries, whichever one employs the Participant.  The
word "subsidiary", when used in the Plan, shall mean any subsidiary corporation
of the Company within the meaning of Section 424(f) of the Internal Revenue
Code of 1986, as amended (the "Code").

                 It is intended that certain options granted under the Plan and
designated as incentive stock options in the option agreements qualify as
"incentive stock options" under Section 422 of the Code.

                 For purposes of the Plan, as amended and restated, the term
"Effective Date" shall mean March 18, 1997.

                                   ARTICLE II

                                 Administration

                 The Plan shall be administered by a Stock Option Committee
(the "Committee") appointed by the Board of Directors of the Company (the
"Board") from among its members and shall consist of not less than two members
thereof.  Unless otherwise determined by the Board, the membership of the
Committee shall be structured so as to qualify option grants for the exemption
from Section 16(b) of the Securities Exchange Act of 1934 (the "Exchange Act")
provided by Rule 16b-3, promulgated by the Securities and Exchange Commission
under the Exchange Act, as in effect from time to time.

                 Subject to the provisions of the Plan, the Committee shall
have sole authority, in its absolute discretion:  (a) to determine which of the
eligible Participants (as hereinafter
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defined) shall be granted options; (b) to authorize the granting of both
incentive stock options and non-qualified stock options; (c) to determine the
times when options shall be granted and the number of shares to be subject to
options; (d) to determine the option price of the shares subject to each
option, which price shall be not less than the minimum specified in ARTICLE V;
(e) to determine the time or times when each option becomes exercisable, the
duration of the exercise period and any other restrictions on the exercise of
options issued hereunder; (f) to accelerate the exercisability of any
outstanding option; (g) to prescribe the form or forms of the option agreements
under the Plan (which forms shall be consistent with the terms of the Plan but
need not be identical and may contain such terms as the Committee may deem
appropriate to carry out the purposes of the Plan); (h) to determine the nature
of any rights and restrictions to be imposed on shares subject to options
issued hereunder; (i) to adopt, amend and rescind such rules and regulations
as, in its opinion, may be advisable in the administration of the Plan; (j) to
construe and interpret the Plan, the option agreements under the Plan and the
rules and regulations adopted from time to time, if any; and (k) to make all
other determinations deemed necessary or advisable for the administration of
the Plan.  All decisions, determinations and interpretations of the Committee
shall be final and binding on all optionees.

                                  ARTICLE III

                                     Stock

                 The stock to be subject to options granted under the Plan
shall be shares of authorized but unissued common stock, par value $0.01 (the
"Stock"), of the Company, or previously issued shares of such Stock reacquired
by the Company and held in its treasury, as determined by the Board.  Under the
Plan, the total number of shares of Stock which may be purchased pursuant to
options granted hereunder shall not exceed, in the aggregate, 1,085,000 shares,
and the maximum number of shares for which options may be granted to any single
optionee during any calendar year shall not exceed 100,000, except as such
numbers of shares shall be adjusted in accordance with the provisions of
ARTICLE X hereof.

                 Each option granted under the Plan shall be evidenced by an
option agreement between the Company and the optionee containing such
provisions as may be determined by the Committee, but shall be subject to the
following terms and conditions:

                 (a) Each share of Stock purchased through the exercise of an
option shall be paid for in full at the time of the exercise; and

                 (b) Each option shall become exercisable by the optionee in
accordance with any vesting schedule established by the Committee pursuant to
ARTICLE VI of the Plan.



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                 The number of shares of Stock available for grant of options
under the Plan shall be decreased by the sum of the number of shares with
respect to which options have been issued and are then outstanding and the
number of shares issued upon exercise of options.  In the event that any
outstanding option for any reason expires, lapses, or is canceled prior to the
end of the period during which options may be granted, the shares of Stock
called for by the unexercised portion of such option may again be subject to an
option under the Plan.

                                   ARTICLE IV

                          Eligibility of Participants

                 Subject to ARTICLE VII, directors, officers, key employees and
consultants of the Company and its subsidiaries who have been selected by the
Committee as participants (collectively referred to as "Participants" and
individually as a "Participant") shall be eligible to receive grants of options
under the Plan; provided, however, that notwithstanding any other provision of
the Plan to the contrary, only employees of the Company or any of its
subsidiaries shall be eligible to receive incentive stock options.
Participation in the Plan shall be limited to eligible Participants who have
entered into option agreements with the Company.  No Participant, however,
shall at any time have a right to be selected for participation in the Plan.

                                   ARTICLE V

                                  Option Price

                 The option price of each option granted under the Plan shall
be determined by the Committee; provided, however, that in the case of each
incentive stock option granted under the Plan, the option price shall not be
less than the fair market value at the time the option is granted.  In no event
shall the option price of any option be less than the par value per share of
Stock on the date an option is granted.

                 At any time when the Stock is quoted on the Nasdaq National
Market ("Nasdaq"), the fair market value shall be deemed to be the closing
price on the trading day immediately preceding the date on which the option is
granted.  If the Stock is listed on one or more national securities exchanges,
the fair market value shall be deemed to be the closing price on the principal
national securities exchange on which such stock is listed and traded on the
trading day immediately preceding the date on which the option is granted.  If
the Stock is not quoted on Nasdaq or listed on an exchange, or representative
quotes are not otherwise available, the fair market value of the Stock shall
mean the amount determined by the Committee to be the fair market value based
upon a good faith attempt to value the Stock accurately and





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computed in accordance with applicable regulations of the Internal Revenue
Service.

                                   ARTICLE VI

                        Terms and Conditions of Options

                 Options granted under the Plan shall vest and become
exercisable in such installments as the Committee shall determine at the time
of grant.  Options may be exercisable in whole or in part and if an option is
exercisable in part, the portion thereof which is exercisable and not exercised
shall remain exercisable.

                 Any other provision of the Plan notwithstanding and subject to
ARTICLE VII, (i) no option shall be granted after the date which is ten years
from the Effective Date, (ii) no option may be exercised after the date which
is ten years after the date that the option was granted (the "Termination
Date"), and (iii) in the event the Company files a registration statement under
the Securities Act of 1933 (the "Securities Act") for the initial public
offering of its equity securities (an "IPO"), the Company may restrict the
exercisability of options granted under the Plan during the 180-day period (or
such longer period required by the underwriter of such initial public offering)
immediately following the effective date of such registration statement.

                 Options granted hereunder may provide that if prior to the
Termination Date an optionee shall cease to be employed by the Employer for any
reason other than death, disability or for cause, the option will remain
exercisable by the optionee for a period not extending beyond three months
after the date of cessation of employment, but in no event later than the
Termination Date, to the extent it was exercisable at the time of cessation of
employment.  Options granted hereunder may provide that if prior to the
Termination Date an optionee shall cease to be employed by the Employer for
reasons of death or disability, the option will remain exercisable by the
optionee or, in the event of his death, by the person or persons to whom the
optionee's rights under the option would pass by will or the applicable laws of
descent and distribution for a period not extending beyond one year after the
date of death or disability, but in no event later than the Termination Date,
to the extent it was exercisable at the time of death or disability.  Options
granted hereunder may provide that if prior to the Termination Date an optionee
shall cease to be employed by the Employer by reason of termination of
employment by the Employer for cause, or by voluntary termination at a time
when the Employer is entitled to terminate such optionee's employment for
cause, the option shall terminate immediately.  For purposes of the Plan, the
Employer shall have "cause" to terminate an optionee's employment hereunder
upon (i) the commission by the optionee of a proven act of fraud or
embezzlement against the Employer, (ii) the engaging by the optionee in willful
misconduct or gross negligence which is demonstrably and materially injurious
to the Employer,





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monetarily or otherwise, (iii) failure of the optionee to render services to
the Employer in accordance with such optionee's duties as an employee of the
Employer or (iv) the optionee being convicted of a misdemeanor involving an act
of moral turpitude or a felony.  Alternatively, options granted hereunder may
provide that "cause" has the meaning set forth in an employment agreement
between the optionee and the Employer.

                 For purposes of the Plan, in the case of a Participant who is
a director, references to employment herein shall be deemed to refer to such
director's service to the Employer in such capacity.

                 Notwithstanding the foregoing, stock options granted hereunder
shall provide that no option shall be exercisable after the optionee's
cessation of employment with the Employer if at the time of exercise the
By-Laws of the Company limit the ownership of common stock of the Company to
selected persons, including employees of the Company and its wholly-owned
subsidiaries.

                                  ARTICLE VII

                         Special Provisions Applicable
                        Only to Incentive Stock Options

                 To the extent the aggregate fair market value (determined at
the time the option is granted) of the Stock with respect to which incentive
stock options may be exercisable for the first time by an optionee during any
calendar year (under this Plan and any other stock option plan of the Company
and any parent or subsidiary thereof) exceeds $100,000, such incentive stock
options shall be treated as options which are non-qualified stock options.

                 No incentive stock option may be granted to an individual who,
at the time the option is granted, owns directly, or indirectly within the
meaning of Section 424(d) of the Code, stock possessing more than 10% of the
total combined voting power of all classes of stock of the Company or of any
parent or subsidiary thereof, unless such option (i) has an option price of at
least 110% of the fair market value of the Stock on the date of the grant of
such option; and (ii) such option by its terms cannot be exercised more than
five years after the date it is granted.

                 Each optionee who receives an incentive stock option must
agree to notify the Company in writing immediately after the optionee makes a
disqualifying disposition of any Stock acquired pursuant to the exercise of an
incentive stock option.  A disqualifying disposition is any disposition
(including any sale) of such Stock before the later of (a) two years after the
date the optionee was granted the incentive stock option or (b) one





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year after the date the optionee acquired Stock by exercising the incentive
stock option.

                                  ARTICLE VIII

                               Payment for Shares

                 Payment for shares of Stock acquired pursuant to an option
granted hereunder shall be made in full, upon exercise of the option, in
immediately available funds in United States dollars, by certified or bank
cashier's check.  Payment may also be made by any other method established by
the Committee including, without limitation, the tendering of previously owned
shares of Stock which have been held for at least six months, or pursuant to
procedures for cashless "broker-assisted" exercises approved by the Committee.
Payment in full shall include payment of any amounts required under paragraph
(b) of ARTICLE XIX.

                                   ARTICLE IX

                 Non-Transferability of Option Rights and Stock

                 During the lifetime of the optionee, the option shall be
exercisable only by the optionee.  No option shall be transferable, except by
will or the laws of descent and distribution.

                                   ARTICLE X

                 Adjustment for Recapitalization, Merger, Etc.

                 The aggregate number of shares of Stock which may be purchased
or acquired pursuant to options granted hereunder, the maximum number of shares
for which options may be granted to any single optionee during any calendar
year, the number of shares of Stock covered by each outstanding option and the
price per share thereof in each such option shall be appropriately adjusted for
any increase or decrease in the number of outstanding shares of Stock resulting
from a stock split or other subdivision or consolidation of shares of Stock or
for other capital adjustments or payments of stock dividends or distributions
or other increases or decreases in the outstanding shares of Stock effected
without receipt of consideration by the Company.  Any adjustment shall be
conclusively determined by the Committee.

                 If the Company shall be the surviving corporation in any
merger or reorganization or other business combination, any option granted
hereunder shall cover the securities or other property to which a holder of the
number of shares of Stock covered by the unexercised portion of the option
would have been entitled pursuant to the terms of the merger.  Upon any merger
or reorganization or other business combination in which the Company shall not
be the surviving corporation, or a dissolution or liquidation of the Company,
or a sale of all or substantially all





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of the Company's assets, all outstanding options shall terminate; provided,
however, that the Company shall cause either (i) the optionees to be paid an
amount equal to the difference between (A) the aggregate fair market value
(determined in accordance with ARTICLE V of the Plan) of the Stock subject to
options held by the optionees at the time of such transaction and (B) the
aggregate exercise price of such options, or (ii) the surviving or resulting
corporation to grant the optionees substitute options to purchase its shares on
such terms and conditions, both as to the number of shares and otherwise, which
the Committee shall deem appropriate.

                 Stock option agreements under the Plan may, at the discretion
of the Committee, provide that upon stockholder approval of a merger,
reorganization or other business combination, whether or not the Company is the
surviving corporation, or a sale of all or substantially all of the Company's
assets, all unmatured installments of the options shall vest and become
immediately exercisable in full.

                 The foregoing adjustments and the manner of application of the
foregoing provisions, including the issuance of any substitute options, shall
be determined by the Committee in its sole discretion.  Any such adjustment may
provide for the elimination of any fractional share which might otherwise
become subject to an option.

                                   ARTICLE XI

                        No Obligation to Exercise Option

                 Granting of an option shall impose no obligation on the
recipient to exercise such option.

                                  ARTICLE XII

                                Use of Proceeds

                 The proceeds received from the sale of Stock pursuant to the
Plan shall be used for general corporate purposes.

                                  ARTICLE XIII

                            Rights as a Stockholder

                 An optionee shall have no rights as a stockholder with respect
to any share covered by his option until such person shall have become the
holder of record of such share, and such person shall not be entitled to any
dividends or distributions or other rights in respect of such share for which
the record date is prior to the date on which such person shall have become the
holder of record thereof, except as otherwise provided in ARTICLE X.





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                                  ARTICLE XIV

                               Employment Rights

                 No provision in the Plan or in any option granted hereunder
shall confer on any optionee any right to continue in the employ of the
Company, or to interfere in any way with the right of the Company to terminate
the optionee's employment at any time.

                                   ARTICLE XV

                              Compliance with Law

                 The Company is relieved from any liability for the
non-issuance or non-transfer or any delay in the issuance or transfer of any
shares of Stock subject to options under the Plan which results from the
inability of the Company to obtain, or from any delay in obtaining, from any
regulatory body having jurisdiction or authority, any requisite approval to
issue or transfer any such shares if counsel for the Company deems such
approval necessary for lawful issuance or transfer thereof.

                 Each option granted under the Plan is subject to the
requirement that if at any time the Board determines, in its discretion, that
the listing, registration or qualification of shares of Stock issuable upon
exercise of options is required by any securities exchange or under any state
or Federal law, or that the consent or approval of any governmental regulatory
body is necessary or desirable as a condition of, or in connection with, the
grant of options or the issuance of shares of Stock, no shares of Stock shall
be issued, in whole or in part, unless such listing, registration,
qualification, consent or approval has been effected or obtained free of any
conditions or with such conditions as are acceptable to the Board.

                                  ARTICLE XVI

                            Cancellation of Options

                 The Committee, in its discretion, may, with the consent of any
optionee, cancel any outstanding option hereunder.

                                  ARTICLE XVII

                    Effective Date; Expiration Date of Plan

                 The Plan, as amended and restated, shall become effective upon
adoption by the Company's Board of Directors and approval by the stockholders
of the Company in a manner which complies with both Section 162(m)(4)(C)(ii)
and Section 422(b)(1) of the Code and the Treasury Regulations thereunder.  The
expiration date of the Plan, after which no option may be granted hereunder,
shall be the tenth anniversary of the earlier of (i)





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adoption of the Plan by the Board of Directors or (ii) the approval of the Plan
by the stockholders of the Company pursuant to the previous sentence.

                                 ARTICLE XVIII

                      Amendment or Discontinuance of Plan

                 The Board may terminate, amend or modify the Plan in its sole
discretion at any time or from time to time after the Effective Date.
Notwithstanding the preceding provisions of this ARTICLE XVIII, no such action
shall, without shareholder approval, increase the number of shares as to which
options may be granted under the Plan.

                                  ARTICLE XIX

                                 Miscellaneous

                 (a) Options shall be evidenced by option agreements (which need
not be identical) in such forms as the Committee may from time to time approve.
Such agreements shall conform to the terms and conditions of the Plan and may
provide that the grant of any option under the Plan and Stock acquired pursuant
to the Plan shall also be subject to such other conditions (whether or not
applicable to the option or Stock received by any other optionee) as the
Committee determines appropriate, including without limitation, provisions to
assist the optionee in financing the purchase of Stock through the exercise of
options, provisions for the forfeiture of, or restrictions on, resale or other
disposition of shares under the Plan, provisions giving the Company the right
to repurchase shares acquired under the Plan in the event the participant
elects to dispose of such shares, and provisions to comply with Federal and
state securities laws and Federal and state income tax withholding
requirements.

                 (b) The Company may, in its discretion,
require that an optionee pay to the Company, at the time of exercise, such
amount as the Company deems necessary to satisfy its obligations to withhold
Federal, state, or local income or other taxes incurred by reason of the
exercise or the transfer of shares thereupon.

                 (c) Each optionee shall file with the Committee a written
designation of one or more persons as beneficiary, who shall be entitled to
exercise options which are exercisable, if any, or to receive shares of Stock
distributable, if any, under the Plan upon the optionee's death.  An optionee
may, from time to time, revoke or change his beneficiary designation without the
consent of any prior beneficiary by filing a new designation with the Committee.
The last such designation received by the Committee shall be controlling;
provided, however, that no designation, or change or revocation thereof, shall
be effective unless received by the Committee prior to the optionee's death,





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and in no event shall it be effective as of a date prior to such receipt.

                 (d) If the Committee shall find that any person to whom any
amount is payable under the Plan is unable to care for his affairs because of
illness or accident, or is a minor, or has died, then any payment due to such
person or his estate (unless a prior claim therefor has been made by a duly
appointed legal representative), may, if the Committee so directs the Company,
be paid to his spouse, child, relative, an institution maintaining or having
custody of such person, or any other person deemed by the Committee to be a
proper recipient on behalf of such person otherwise entitled to payment.  Any
such payment shall be a complete discharge of the liability of the Committee
and the Company therefor.

                 (e) No member of the Committee shall be personally liable by
reason of any contract or other instrument executed by such member or on his
behalf in his capacity as a member of the Committee nor for any mistake of
judgment made in good faith, and the Company shall indemnify and hold harmless
each member of the Committee and each other employee, officer or director of
the Company to whom any duty or power relating to the administration or
interpretation of the Plan may be allocated or delegated, against any cost or
expense (including counsel fees) or liability (including any sum paid in
settlement of a claim) arising out of any act or omission to act in connection
with the Plan unless arising out of such person's own fraud or bad faith;
provided, however, that approval of the Board shall be required for the payment
of any amount in settlement of a claim against any such person.  The foregoing
right of indemnification shall not be exclusive of any other rights of
indemnification to which such persons may be entitled under the Company's
Certificate of Incorporation or By-Laws, as a matter of law, or otherwise, or
any power that the Company may have to indemnify them or hold them harmless.

                 (f) The Plan shall be governed by and construed in accordance
with the internal laws of the State of Delaware without reference to the
principles of conflicts of law thereof.

                 (g) No provision of the Plan shall require the Company, for the
purpose of satisfying any obligations under the Plan, to purchase assets or
place any assets in a trust or other entity to which contributions are made or
otherwise to segregate any assets, nor shall the Company maintain separate bank
accounts, books, records or other evidence of the existence of a segregated or
separately maintained or administered fund for such purposes.  Optionees shall
have no rights under the Plan other than as unsecured general creditors of the
Company, except that insofar as they may have become entitled to payment of
additional compensation by performance of services, they shall have the same
rights as other employees under general law.





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                 (h)   Each member of the Committee and each member of the Board
shall be fully justified in relying, acting or failing to act, and shall not be
liable for having so relied, acted or failed to act in good faith, upon any
report made by the independent public accountant of the Company and upon any
other information furnished in connection with the Plan by any person or
persons other than such member.

                 (i)   Except as otherwise specifically provided in the relevant
plan document, no payment under the Plan shall be taken into account in
determining any benefits under any pension, retirement, profit-sharing, group
insurance or other benefit plan of the Company.

                 (j)   The expenses of administering the Plan shall be borne by
the Company.

                 (k)   Masculine pronouns and other words of masculine gender
shall refer to both men and women. 

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                    FORM OF INCENTIVE STOCK OPTION AGREEMENT

         This Option Agreement (the "Agreement), is made as of this _____ day
of __________, _____ (the "Date of Grant") between CN Biosciences, Inc., a
Delaware corporation (the "Company"), and the person signing this Agreement
adjacent to the caption "Participant" on the signature page hereof, which
person is an employee (the "Participant") of the Company and/or one or more of
its subsidiaries (the "Employer").  Capitalized terms used and not otherwise
defined herein shall have the meanings attributed thereto in the CN
Biosciences, Inc. Amended and Restated 1992 Stock Option Plan (the "Plan").

         WHEREAS, pursuant to the Plan, the Company desires to afford the
Participant the opportunity to purchase shares of the Company's Common Stock,
par value $.01 per share (the "Stock");

         NOW, THEREFORE, in connection with the mutual covenants hereinafter
set forth and for other good and valuable consideration, the parties hereto
agree as follows:

         1.      Grant of Options.  The Company hereby grants to the
Participant the right and option (the right to purchase any one share of Stock
pursuant to the Plan being an "Option") to purchase an aggregate _____ shares
of Stock, such shares being subject to adjustment as provided in ARTICLE X of
the Plan, and on the terms and conditions herein set forth.

         2.      Purchase Price.  The purchase price of each share of Stock
covered by the Options shall be equal to $_____ per share.

         3.      Terms of Options.  The term of the Options shall be for a
period of _____ (_) years from the Date of Grant.

         4.      Vesting of Options.  Subject to the terms, conditions and
limitations contained herein, ________ percent (__%) of the Options granted
hereunder shall vest and become exercisable on the first anniversary of the
Date of Grant, and an additional _________ percent (__%) of the Options granted
hereunder shall vest on each of the next ____ anniversaries of such Date of
Grant.  Notwithstanding the above, one hundred percent (100%) of the Options
granted hereunder shall vest and become exercisable upon a Change of Control of
the Company.  For this purpose, a "Change of Control" shall mean (a) an
acquisition (other than directly from the Company) by an individual, entity or
a group (excluding the Company, an employee benefit plan of the Company or E.M.
Warburg, Pincus & Co., LLC or its affiliates) of 50% or more of the Company's
Common Stock or voting securities; (b) a change in a majority of the Company's
current Board of Directors (the "Incumbent Board") (excluding any persons
approved by a vote of a least a majority of the Incumbent Board or persons
elected with the concurrence of a majority of the Incumbent Board); or
<PAGE>   13




(c) the consummation of a complete liquidation or dissolution of the
Company or a merger, consolidation or sale off all or substantially all of the
Company's assets (collectively, a "Business Combination") other than a Business
Combination in which all or substantially all of the Company's stockholders
receive 50% or more of the stock of the company resulting from the Business
Combination, at least a majority of the board of directors of the resulting
corporation were members of the Incumbent Board, and after which no Person owns
50% or more of the stock of the resulting corporation, who did not own such
stock immediately before the Business Combination.

         5.      Termination of Employment.  (a) In the event the Participant's
employment with the Employer is terminated for reasons other than due to death,
disability or cause (as defined in the Plan), the Options shall remain
exercisable for a period of up to three months after cessation of employment,
to the extent they were exercisable at the time of cessation of employment.  In
the event the Participant's employment with the Employer terminates by death or
disability, the Options shall remain exercisable for a period of up to twelve
months after cessation of employment, to the extent they were exercisable at
the time of cessation of employment.

                 (b)      If the Participant's employment with the Employer is
terminated for cause, or, at the time of the Participant's voluntary
termination, the Employer is entitled to terminate the Participant for cause
(as defined in the Plan), all unexercised Options granted to the Participant
shall lapse and be canceled.

         6.      Transferability of Option and Stock.  The Participant is not
allowed to transfer the Options other than by will or the laws of descent and
distribution, and the Options shall be exercisable during the Participant's
lifetime, only by him.

         7.      No Rights as a Shareholder.  The Participant shall have no
rights as a shareholder with respect to any shares of Stock covered by the
Options until the date of issuance of a certificate for such Stock.  No
adjustment, other than as provided in ARTICLE X of the Plan, shall be made for
dividend (ordinary or extraordinary, whether in cash, securities or other
property) or distribution for which the record date is prior to the date such
stock certificate is issued.

         8.      Securities Law Compliance.  No Stock will be issued hereunder
unless counsel for the Company shall be satisfied that such issuance will be in
compliance with applicable federal and state securities law.

         9.      Method of Exercising Option.  Subject to the terms and
conditions of this Agreement and the Plan, the Options may be exercised by
written notice to the Company at its offices located in San Diego, California.
Such notice shall state the election to exercise Options and the number of
shares of Stock in respect





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of which they are being exercised, and shall be signed by the person or persons
so exercising the Option.  Such notice shall either:

                 (a)      be accompanied by payment of the full purchase price
of such share of Stock, in which event the Company shall cause to be delivered
a certificate or certificates representing such shares of Stock as soon as
practicable after the notice shall be received;

                 (b)      fix a date, not less than five (5) nor more than ten
(10) business days from the date such notice shall be received by the Company,
for the payment of the full purchase price of such shares of Stock against
delivery of a certificate or certificates representing such shares of Stock.

                 Payment of such purchase price shall be made in United States
dollars by either: (a) certified check or bank cashier's check payable to the
order of the Company, or (b) upon the Committee's approval, any other method
including, without limitation, the tendering of previously owned shares of
Stock which have been held by the Participant for at least six months, or
pursuant to procedures for cashless "broker-assisted" exercises established by
the Committee.  The certificate or certificates for the shares of Stock as to
which the Options shall have been so exercised shall be registered in the name
of the person or persons so exercising the Options; or if the Options shall be
exercised by the Participant, and if the Participant shall so request in the
notice exercising the Options, such shares shall be registered in the name of
the Participant and other person, as joint tenant with right of survivorship,
and shall be delivered as provided above to or upon the written order of the
person or persons exercising the Options.  All shares of Stock that shall be
purchased upon the exercise of Options as provided herein shall be fully paid
and non-assessable.

         10.     Income Tax Withholding.  The Company may make such provisions
and take such steps as it may deem necessary or appropriate for the withholding
of all Federal, State, local or other taxes required by law to be withheld with
respect to an Option, including, but not limited to, deducting the amount of
any such withholding taxes from the amount to be paid hereunder, whether in
Stock or in cash, or from any other amount then or thereafter payable to the
optionee, or requiring the Participant, his beneficiary or legal
representative, to pay to the Company the amount required to be withheld or to
execute such documents as the Company deems necessary or desirable to enable it
to satisfy its withholding obligations.

         11.     Incentive Stock Options.  The Options granted hereunder are
intended to be incentive stock options within the meaning of Section 422 of the
Code.





                                      -3-
<PAGE>   15




         12.     Binding Effect.  This Agreement shall be binding upon the
heirs, executors, administrators and successors of the parties hereto.

         13.     Governing Law.  This Agreement shall be construed and
interpreted in accordance with the law of the State of Delaware.

         14.     Headings.  Headings are for the convenience of the parties and
are not deemed to be part of this Agreement.

         15.     Plan.  The terms and provisions of the Plan are incorporated
herein by reference.  In the event of a conflict or inconstancy between
discretionary terms and provisions of the Plan and the express provision of
this Agreement, this Agreement shall govern and control.  In all other
instances of conflicts or inconsistencies or omissions, the terms and
provisions of the Plan shall govern and control.

         EXECUTED the day and year first written above.


COMPANY:                                CN BIOSCIENCES, INC.

                                        By: ______________________________
                                            Name:
                                            Title:
PARTICIPANT:
                                        By: ______________________________
                                            Name:
                                            Title:





                                      -4-
<PAGE>   16
                  FORM OF NONQUALIFIED STOCK OPTION AGREEMENT

         This Option Agreement (the "Agreement), is made as of this _____ day
of __________, _____ (the "Date of Grant") between CN Biosciences, Inc., a
Delaware corporation (the "Company"), and the person signing this Agreement
adjacent to the caption "Participant" on the signature page hereof, which
person is a director, officer, key employee or consultant (the "Participant")
of the Company and/or one or more of its subsidiaries (the "Employer").
Capitalized terms used and not otherwise defined herein shall have the meanings
attributed thereto in the CN Biosciences, Inc. Amended and Restated 1992 Stock
Option Plan (the "Plan").

         WHEREAS, pursuant to the Plan, the Company desires to afford the
Participant the opportunity to purchase shares of the Company's Common Stock,
par value $.01 per share (the "Stock");

         NOW, THEREFORE, in connection with the mutual covenants hereinafter
set forth and for other good and valuable consideration, the parties hereto
agree as follows:

         1.      Grant of Options.  The Company hereby grants to the
Participant the right and option (the right to purchase any one share of Stock
pursuant to the Plan being an "Option") to purchase an aggregate _____ shares
of Stock, such shares being subject to adjustment as provided in ARTICLE X of
the Plan, and on the terms and conditions herein set forth.

         2.      Purchase Price.  The purchase price of each share of Stock
covered by the Options shall be equal to $_____ per share.

         3.      Terms of Options.  The term of the Options shall be for a
period of _____ (_) years from the Date of Grant.

         4.      Vesting of Options.  Subject to the terms, conditions and
limitations contained herein, ________ percent (__%) of the Options granted
hereunder shall vest and become exercisable on the first anniversary of the
Date of Grant, and an additional _________ percent (__%) of the Options granted
hereunder shall vest on each of the next ____ anniversaries of such Date of
Grant.  Notwithstanding the above, one hundred percent (100%) of the Options
granted hereunder shall vest and become exercisable upon a Change of Control of
the Company.  For this purpose, a "Change of Control" shall mean (a) an
acquisition (other than directly from the Company) by an individual, entity or
a group (excluding the Company, an employee benefit plan of the Company or E.M.
Warburg, Pincus & Co., LLC or its affiliates) of 50% or more of the Company's
Common Stock or voting securities; (b) a change in a majority of the Company's
current Board of Directors (the "Incumbent Board") (excluding any persons
approved by a vote of a least a majority of the Incumbent Board or persons
elected
<PAGE>   17




with the concurrence of a majority of the Incumbent Board); or (c)
the consummation of a complete liquidation or dissolution of the Company or a
merger, consolidation or sale off all or substantially all of the Company's
assets (collectively, a "Business Combination") other than a Business
Combination in which all or substantially all of the Company's stockholders
receive 50% or more of the stock of the company resulting from the Business
Combination, at least a majority of the board of directors of the resulting
corporation were members of the Incumbent Board, and after which no Person owns
50% or more of the stock of the resulting corporation, who did not own such
stock immediately before the Business Combination.

         5.      Termination of Employment or Service.  (a) In the event the
Participant's employment or service with the Employer is terminated for reasons
other than due to death, disability or cause (as defined in the Plan), the
Options shall remain exercisable for a period of up to three months after
cessation of employment or service, to the extent they were exercisable at the
time of cessation of employment or service.  In the event the Participant's
employment or service with the Employer terminates by death or disability, the
Options shall remain exercisable for a period of up to twelve months after
cessation of employment or service, to the extent they were exercisable at the
time of cessation of employment or service.

                 (b)      If the Participant's employment or service with the
Employer is terminated for cause, or, at the time of the Participant's
voluntary termination, the Employer is entitled to terminate the Participant
for cause (as defined in the Plan), all unexercised Options granted to the
Participant shall lapse and be canceled.

         6.      Transferability of Option and Stock.  The Participant is not
allowed to transfer the Options other than by will or the laws of descent and
distribution, and the Options shall be exercisable during the Participant's
lifetime, only by him.

         7.      No Rights as a Shareholder.  The Participant shall have no
rights as a shareholder with respect to any shares of Stock covered by the
Options until the date of issuance of a certificate for such Stock.  No
adjustment, other than as provided in ARTICLE X of the Plan, shall be made for
dividend (ordinary or extraordinary, whether in cash, securities or other
property) or distribution for which the record date is prior to the date such
stock certificate is issued.

         8.      Securities Law Compliance.  No Stock will be issued hereunder
unless counsel for the Company shall be satisfied that such issuance will be in
compliance with applicable federal and state securities law.

         9.      Method of Exercising Option.  Subject to the terms and
conditions of this Agreement and the Plan, the Options may be





                                      -2-
<PAGE>   18




exercised by written notice to the Company at its offices located in San Diego,
California.  Such notice shall state the election to exercise Options and the
number of shares of Stock in respect of which they are being exercised, and
shall be signed by the person or persons so exercising the Option.  Such notice
shall either:

                 (a)      be accompanied by payment of the full purchase price
of such share of Stock, in which event the Company shall cause to be delivered
a certificate or certificates representing such shares of Stock as soon as
practicable after the notice shall be received;

                 (b)      fix a date, not less than five (5) nor more than ten
(10) business days from the date such notice shall be received by the Company,
for the payment of the full purchase price of such shares of Stock against
delivery of a certificate or certificates representing such shares of Stock.

                 Payment of such purchase price shall be made in United States
dollars by either: (a) certified check or bank cashier's check payable to the
order of the Company, or (b) upon the Committee's approval, any other method
including, without limitation, the tendering of previously owned shares of
Stock which have been held by the Participant for at least six months, or
pursuant to procedures for cashless "broker-assisted" exercises established by
the Committee.  The certificate or certificates for the shares of Stock as to
which the Options shall have been so exercised shall be registered in the name
of the person or persons so exercising the Options; or if the Options shall be
exercised by the Participant, and if the Participant shall so request in the
notice exercising the Options, such shares shall be registered in the name of
the Participant and other person, as joint tenant with right of survivorship,
and shall be delivered as provided above to or upon the written order of the
person or persons exercising the Options.  All shares of Stock that shall be
purchased upon the exercise of Options as provided herein shall be fully paid
and non-assessable.

         10.     Income Tax Withholding.  The Company may make such provisions
and take such steps as it may deem necessary or appropriate for the withholding
of all Federal, State, local or other taxes required by law to be withheld with
respect to an Option, including, but not limited to, deducting the amount of
any such withholding taxes from the amount to be paid hereunder, whether in
Stock or in cash, or from any other amount then or thereafter payable to the
optionee, or requiring the Participant, his beneficiary or legal
representative, to pay to the Company the amount required to be withheld or to
execute such documents as the Company deems necessary or desirable to enable it
to satisfy its withholding obligations.





                                      -3-
<PAGE>   19




         11.     Nonqualified Stock Options.  The Options granted hereunder are
not intended to be incentive stock options within the meaning of Section 422 of
the Code.

         12.     Binding Effect.  This Agreement shall be binding upon the
heirs, executors, administrators and successors of the parties hereto.

         13.     Governing Law.  This Agreement shall be construed and
interpreted in accordance with the law of the State of Delaware.

         14.     Headings.  Headings are for the convenience of the parties and
are not deemed to be part of this Agreement.

         15.     Plan.  The terms and provisions of the Plan are incorporated
herein by reference.  In the event of a conflict or inconstancy between
discretionary terms and provisions of the Plan and the express provision of
this Agreement, this Agreement shall govern and control.  In all other
instances of conflicts or inconsistencies or omissions, the terms and
provisions of the Plan shall govern and control.

         EXECUTED the day and year first written above.



COMPANY:                                CN BIOSCIENCES, INC.

                                        By: ______________________________
                                            Name:
                                            Title:
PARTICIPANT:
                                        By: ______________________________
                                            Name:
                                            Title:





                                      -4-